Manifold designs, and flow control in multichannel microchannel devices

ABSTRACT

Novel manifolds and methods of flow through manifolds are described. Apparatus and techniques are described in which flow from a relatively large volume header is equally distributed to process channels. Methods of making laminated, microchannel devices are also described.

In recent years there has been intense industrial and academic interesttoward developing microscale devices for chemical processing. A recentreview of microscale reactors, containing 236 citations, has beenprovided by Gavrilidis et al., “Technology And Applications OfMicroengineered Reactors,” Trans. IChemE, Vol. 80, Part A, pp. 3-30(Jan. 2002). Microscale chemical processors, which are characterized byfluid channel dimensions of about 5 mm or less, can provide uniqueadvantages due to short heat and mass transfer distances, and, in someinstances, different flow characteristics. Although these devices mayoffer many advantages, new designs and differing flow characteristicswithin these devices create challenges for creating new methods anddesigns for controlling flow, particularly flow through a manifold andseveral connecting channels. In particular, the small channel dimensionsthat give rise to improved heat and mass transport can often be in thelaminar flow regime, which in turn carries a lower flow resistance thantransition and turbulent flow regimes. A laminar regime can exist evenfor very high flow rates due to the small dimensions of the channels.Thus, a large microchannel processing device could have relatively smallpressure drops at high overall flow rate, adding to the flowdistribution challenge due to low flow resistance. Further, microscaledevices are connected to macro pipes to bring in and remove fluids. Flowin the macro-pipes is often in the turburlent or transition regime, thusrequiring flow manifolding solutions within the microdevice thatdistribute flow to many parallel microchannels under varying flowregimes.

The recent patent literature describes multiple types of microscaledevices and/or methods of manufacture. For example, Wegeng et al., in WO01/95237 A2, described novel types of integrated reactors that are madeby laminated sheets of numerous different designs. Pence et al., in US2002/0080563 A1, described devices with a network of branchingmicrochannels for heat transport.

Golbig et al., in U.S. Patent Application Publication 2002/0106311described plate microreactor designs in which the widths of connectingchannels are varied in order to provide equalized residence time offluids in the channels. Calculations based on this design, as describedin the Examples section, show that this design is inadequate forobtaining highly equal flow from a header through all connectingchannels.

Channel designs for controlling flow in compact heat exchangers andother compact devices, have been described in Patent Applications Nos.and U.S. Pat. Nos. 3,847,211, 5,482,680, 4,401,155, 2002/0043544,4,343,354, 6,293,338, 4,041,591, 5,915,469, 6,098,706, 4,282,927,2003/0027354, 2002/0125001, 2002/0187090, 6,244,333, and 5,544,700.

Despite these and other efforts, there is still a need for methods ofcontrolling flow and apparatus in which flow is controlled to obtainimproved performance and efficiency.

SUMMARY OF THE INVENTION

In one aspect, the invention provides a method of separating phases,comprising: passing a mixture into a curve in a microchannel; wherein,after the curve, there is a separator plate in the microchannel; andwherein the mixture separates into a denser phase and a less dense phasewith the different phases on opposite sides of the separator plate. Inpreferred embodiments, flow is down substantially parallel to gravityinto the curve. The invention also provides this apparatus.

In another aspect, the invention provides a fluid processor, comprising:a manifold comprising an inlet; a connecting channel matrix; and a gatedisposed between the manifold and the connecting channel matrix. Thelength of the manifold and the length of the connecting channel matrixare disposed at a nonzero angle relative to each other. The connectingchannel matrix served by the gate has a central axis; and the gate isoffset so that the gates opening is not bisected by the central axis ofthe connecting channel matrix. One example of this aspect is illustratedin FIG. 24. In some preferred embodiments, the length of the manifold issubstantially perpendicular to the length of the connecting channels.Preferably, in this aspect the offset is at least 10% (in some preferredembodiments at least 25%) of the width of the connecting channel matrix.

As with all the apparatus described herein, the invention also providesmethods of processing a fluid comprising passage of at least one fluidthrough the apparatus. As shown in the drawings, the manifold andconnecting channel matrix can be coplanar; indeed substantially coplanararrangements are common throughout many aspects of the present inventionand it should be understood that a coplanar arrangement is preferred inmany aspects of the invention. It should also be understood that theinvention is intended to include combinations of the various aspects andfeatures described herein. For example, in some preferred embodiments,the gates offsets described in the foregoing aspect are combined withthe variance in the extension of connecting channel walls described inthe aspect below. It should be further understood that the invention isintended to include multiple combinations of the described individualfeatures and should not be limited to only the illustrated combinationsor the combinations that are described herein.

In another aspect, also illustrated in FIG. 24, the invention provides afluid processor, comprising: a manifold comprising an inlet; and aconnecting channel matrix. The length of the manifold and the length ofthe connecting channel matrix are disposed at a nonzero angle relativeto each other. The connecting channel matrix comprises multiple channelwalls and channel walls further from the inlet extend further toward themanifold. In some preferred embodiments: the length of the manifold issubstantially perpendicular to the length of the connecting channels;and/or, the offset is at least 10% (in some preferred embodiments atleast 25%) of the width of the connecting channel matrix.

In another aspect, the invention provides a method of passing a fluidthrough a manifold of a microchannel device, comprising: flowing a firstfluid stream through a first channel in a first direction; flowing aportion of the first fluid stream through an aperture to a secondchannel; and flowing a portion of the first fluid stream through thesecond channel; wherein the second channel extends at a nonzero anglerelative to the first direction; wherein flow through the aperture has apositive momentum vector in the first direction; wherein the secondchannel comprises a microchannel and comprises at least one dividingwall that separates the second channel into at least a first and asecond subchannel; wherein the second channel has an axis that issubstantially parallel to net flow through the second channel; andwherein the aperture has a centerpoint that lies upstream of the axisrelative to the first direction. Preferably, in this method, flow in thefirst and second subchannels is more equal than if the axis passedthrough the centerpoint. A preferred structure in which this method canbe conducted is illustrated in FIG. 24.

In another aspect, the invention provides a method of passing a fluidthrough a manifold of a microchannel device, comprising: flowing a firstfluid stream through a first channel in a first direction; flowing aportion of the first fluid stream through an aperture to a secondchannel; and flowing a portion of the first fluid stream through thesecond channel. The second channel comprises a microchannel andcomprises at least one dividing wall that separates the second channelinto at least a first and a second subchannel. The first and secondsubchannels comprise flow resistors that tend to equalize flow throughthe subchannels. A structure suitable for conducting this method isillustrated in FIG. 25 b. As with all methods described herein, theinvention also includes the apparatus in which the method is conducted.In some preferred embodiments, the second channel extends at a nonzeroangle relative to the first direction. In other embodiments, the methodcan be conducted in a laminated device with frames or strips; and/orflow resistors (such as a foam); and/or where there is no straightthrough flow path; and/or where there is a discontinuity in the dividingwall downstream along the length of the dividing wall. It should beunderstood that, as with other inventive aspects, in some preferredembodiments, the manifold and connecting channels are substantiallycoplanar.

In another aspect, the invention provides microchannel apparatus,comprising at least two microchannels separated by a wall; and aflexible material projecting from the wall into at least into at leastone of the microchannels. See FIG. 33. “Flexible” means that thematerial flexes when fluid flows through the microchannel. In oneembodiment, the material extends through the wall into a secondmicrochannel.

In another aspect, the invention provides microchannel apparatus,comprising: a first channel extending in a first direction; and a secondchannel extending in a second direction. In this apparatus, the firstdirection and second direction are substantially coplanar and extend ata nonzero angle relative to each other; the second channel comprises amicrochannel; and the second channel comprises a first open portion anda second portion that comprises at least one dividing wall thatseparates the second channel into at least a first and a secondsubchannel. The first open portion provides for a length for flow todistribute more equally across the stream prior to entering the secondportion. “Open” means no subchannels. An example is illustrated in FIG.25 a. The invention also includes methods of processing a fluid in thisapparatus, preferably in which mixing occurs in the first portion. In apreferred embodiment, L₂/D is greater than 10, where D is hydraulicdiameter. In preferred embodiments, the subchannels are connectingchannels in which a unit operation occurs.

In another aspect, the invention provides microchannel apparatus,comprising: a first channel comprising a first open portion and a secondportion; the second portion comprising at least one dividing wall thatseparates the second portion into at least a first and a secondsubchannel; the first channel extending in a first direction; a secondchannel connected to first subchannel; wherein the second channel issubstantially coplanar with the first channel and extends in a seconddirection; wherein the second direction is at a nonzero angle relativeto the first direction; wherein the second channel comprises amicrochannel and comprises at least one dividing wall that separates thesecond channel into at least a third and a fourth subchannel; a thirdchannel connected to second subchannel; wherein the third channel issubstantially coplanar with the first channel and extends in a thirddirection; wherein the third direction is substantially parallel to thesecond direction; wherein the third channel comprises a microchannel andcomprises at least one dividing wall that separates the third channelinto at least a fifth and a sixth subchannel. An example is illustratedin FIG. 3E. For purposes of this aspect, subchannels are formed bydividing a channel such as with a fin, but subchannels are not channels,such as formed by a T-joint, that are substantially separated in space.

In another aspect, the invention provides microchannel apparatusincluding a submanifold, comprising: a first channel comprising at leastone dividing wall that separates the first channel into at least a firstand a second subchannel; the first channel extending in a firstdirection; a second channel connected to the first subchannel; whereinthe second channel is substantially coplanar with the first channel andextends in a second direction; wherein the second direction is at anonzero angle relative to the first direction; wherein the secondchannel comprises a microchannel and comprises at least one dividingwall that separates the second channel into at least a third and afourth subchannel; a third channel connected to the second subchannel;wherein the third channel is substantially coplanar with the firstchannel and extends in a third direction; wherein the third direction isparallel to the second direction; wherein the third channel comprises amicrochannel and comprises at least one dividing wall that separates thethird channel into at least a fifth and a sixth subchannel; wherein thefirst subchannel has a first length and a first width and the secondsubchannel has a second length and a second width; and wherein thesecond length is longer than the first length. In one preferredembodiment, the first channel comprises a first portion with no channelwall and a second portion that comprises the at least one dividing wallthat separates the first channel into at least a first and a secondsubchannel; and the second width is wider than the first width. Somepreferred embodiment comprise gates. In another embodiment, a fourthchannel is connected to the second subchannel; wherein the fourthchannel is substantially coplanar with the first channel and extends ina fourth direction; wherein the fourth direction is at a nonzero anglerelative to the first direction; wherein the fourth channel comprises amicrochannel and comprises at least one dividing wall that separates thesecond channel into at least a seventh and an eighth subchannel; whereinthe fourth direction is parallel to the second direction; and whereinthe fourth channel has a fourth length that is longer than the secondlength.

In another aspect, the invention provides microchannel apparatusincluding a gated structure, comprising: a first channel extending in afirst direction; a second channel extending in a second direction; and athird channel extending in the second direction; a fourth channelextending in the second direction; and a fifth channel extending in thesecond direction. The first and second directions are substantiallycoplanar. The second and third channels are adjacent and parallel. Thefirst channel is not parallel to either the second or third channels.The first channel is connected to the second channel and the thirdchannels via a first gate. The third channel is positioned farther inthe first direction than the second channel. The third channel comprisesa microchannel. The second channel comprises a microchannel. The secondchannel has an opening with a first cross-sectional area and the thirdchannel has an opening with a second cross-sectional area. The firstgate has a cross-sectional area that is smaller than the sum of firstand second cross-sectional areas and the wall cross-sectional areabetween them. The fourth and fifth channels are adjacent and parallel.The first channel is connected to the fourth channel and the fifthchannels via a second gate. The fourth and fifth channels are positionedfarther in the first direction than the third channel. The fourthchannel comprises a microchannel; wherein the fifth channel comprises amicrochannel. The fourth channel has an opening with a thirdcross-sectional area and the fifth channel has an opening with a fourthcross-sectional area. The second gate has a cross-sectional area that issmaller than the sum of third and fourth cross-sectional areas and thewall cross-sectional area between them; and the cross-sectional area ofthe first gate differs from that of the cross-sectional area of thesecond gate. In a preferred embodiment, the first gate has across-sectional area between 2-98% of the combined cross-sectional areasof the connecting microchannels served by the first gate. In anotherembodiment, the apparatus is a laminate and the first gate comprises asheet with a cross-bar.

In another aspect, the invention provides microchannel apparatus,comprising: a first channel extending in a first direction; a secondchannel extending in a second direction; and a third channel extendingin a third direction. The first, second, and third directions aresubstantially coplanar. The second and third directions are parallel.The second channel connects to the first channel and the first andsecond directions extend at a nonzero angle relative to each other. Thethird channel connects to the first channel and the first and thirddirections extend at a nonzero angle relative to each other. The thirdchannel is positioned farther in the first direction than the secondchannel. The third channel comprises a microchannel. The second channelhas an opening with a first cross-sectional area and the third channelhas an opening with a second cross-sectional area. The firstcross-sectional area is of a different cross-sectional area than thesecond width; and the at least one of the openings is smaller incross-sectional area then the connecting channel it connects to themanifold. This aspect is an example of a “grate” structure. In apreferred embodiment, the second and third channels have openings thatare adjacent to an opening of the first channel. In another embodiment,the second and third channels are adjacent channels separated by achannel wall. In another embodiment, a second grate is disposed in thesecond and third channels. In preferred embodiments, the open areathrough a grate is smaller than the open areas of the channels which thegrates open into; however, in some cases this area could be larger—forexample, by etching the walls.

It should be understood that any of the apparatus, systems or methodscan be characterized by the equations or quality factors discussed laterin the text.

In another aspect, the invention provides a laminated device,comprising: a first layer comprising microchannels that end in a firstcrossbar; and a second layer comprising microchannels that end in asecond crossbar; wherein the first crossbar defines at least a portionof one edge of an M2M manifold; wherein the second crossbar projectsinto the M2M manifold; and wherein an interface between themicrochannels in the second layer and the manifold is formed by an opengap between the first and second crossbars. An example is shown in FIG.3D. Preferably, the first layer is adjacent to the second layer. Also,in a preferred embodiment, the device includes microchannels in firstand second layers that are aligned. In another embodiment, the laminateddevice further comprises: a second set of microchannels in the firstlayer that end in a third crossbar; and a second set of microchannels inthe second layer that end in a fourth crossbar; wherein the thirdcrossbar defines at least a portion of one edge of the M2M manifold;wherein the fourth crossbar projects into the M2M manifold; wherein asecond interface between the microchannels in the fourth layer and themanifold is formed by an open gap between the third and fourthcrossbars; and wherein the open gap between the third and fourthcrossbars is smaller than the open gap between the first and secondcrossbars. The differing gap size allows systems to be designed tocontrol flow though the microchannels (i.e., function like a gate); forexample to make flow more equal than if the gaps were equal. Systemsincluding a macromanifold connected to at least two of the laminateddevices and methods of conducting a unit operation comprising passing afluid into the manifold and through the microchannels, are, of course,included.

In another aspect, the invention provides a method of distributing flowfrom a manifold through a connecting channel matrix, comprising:

passing a fluid through a manifold inlet and into a manifold having thefollowing characteristics:

the height of the manifold (h_(m2m)) is 2 mm or less;

the length of the manifold (L_(m2m)) is 7.5 cm or greater;

the length of an optional straightening channel portion (L₂) divided byL_(m2m) is less than 6;

passing the fluid into the manifold with a momentum (Mo) of at least0.05; maintaining the DPR₂ ratio at 2 or greater or maintaining a DPR₃ratio of 0.9 or less;and distributing the fluid from the manifold into at least 2 channelswhich are connected to the manifold, with a quality index factor as afunction of connecting channel areas of equal to or less than Q(Ra),where:

Q(Ra)=0.0008135Ra ⁶−0.03114Ra ⁵+0.4519Ra ⁴−3.12Ra ³+11.22Ra²−23.9Ra+39.09.

Preferably, R_(a) is equal to or less than 12, or less than 3. In someembodiments, the fluid flow rate through the manifold is maintained suchthat the quantity {|0.058+0.0023(ln Re)²(D)|/L_(M2M)} is less than 0.01.In some embodiments, FA is less than 0.01

In another aspect, the invention provides a method of distributing flowfrom a manifold through a connecting channel matrix, comprising:

passing a fluid into a manifold having the following characteristics:

the height of the manifold is 2 mm or less;

the length of an optional straightening channel portion (L₂) divided byL_(M2M) is less than 6;

with a FA value of less than 0.01

${FA} = {\frac{\left\lbrack {0.058 + {0.0023\left( {\ln \mspace{14mu} {Re}} \right)^{2}}} \right\rbrack^{2}D}{L_{M\; 2M}} < 0.01}$

maintaining the DPR₂ ratio at 2 or greater or maintaining a DPR₃ ratioof 0.9 or less; and distributing the fluid from the manifold into atleast 2 channels, which are connected to the manifold, with a qualityindex factor as a function of connecting channel areas of Q₂ equal to orless than 85% of the Q_(c) function of connecting channel area ratio Raand DPR₁ of

Q _(c)(Ra,DPR ₁)=E1+E2+E4+E6+E8+E10+E12,

where

${E\; 1} = {\frac{112.9 + {1.261{DPR}_{1}}}{1 + {0.3078{DPR}_{1}} + {0.003535{DPR}_{1}^{2}}}{\quad{{\left\lbrack \frac{\left( {{Ra} - 2} \right)\left( {{Ra} - 4} \right)\left( {{Ra} - 6} \right)\left( {{Ra} - 8} \right)\left( {{Ra} - 10} \right)\left( {{Ra} - 12} \right)}{\left( {1 - 2} \right)\left( {1 - 4} \right)\left( {1 - 6} \right)\left( {1 - 8} \right)\left( {1 - 10} \right)\left( {1 - 12} \right)} \right\rbrack E\; 2} = {\frac{91.73 - {1.571{DPR}_{1}} + {0.01701{DPR}_{1}^{2}}}{1 + {0.2038{DPR}_{1}} + {0.00193{DPR}_{1}^{2}}}{\quad{{\left\lbrack \frac{\left( {{Ra} - 1} \right)\left( {{Ra} - 4} \right)\left( {{Ra} - 6} \right)\left( {{Ra} - 8} \right)\left( {{Ra} - 10} \right)\left( {{Ra} - 12} \right)}{\left( {2 - 1} \right)\left( {2 - 4} \right)\left( {2 - 6} \right)\left( {2 - 8} \right)\left( {2 - 10} \right)\left( {2 - 12} \right)} \right\rbrack E\; 4} = {{{\frac{24.27 - {4.943{DPR}_{1}} + {0.3982{DPR}_{1}^{2}}}{1 - {0.2395{DPR}_{1}} + {0.03442{DPR}_{1}^{2}} - {0.000006657{DPR}_{1}^{3}}}\left\lbrack \frac{\left( {{Ra} - 1} \right)\left( {{Ra} - 2} \right)\left( {{Ra} - 6} \right)\left( {{Ra} - 8} \right)\left( {{Ra} - 10} \right)\left( {{Ra} - 12} \right)}{\left( {4 - 1} \right)\left( {4 - 2} \right)\left( {4 - 6} \right)\left( {4 - 8} \right)\left( {4 - 10} \right)\left( {4 - 12} \right)} \right\rbrack}E\; 6} = {\frac{29.23 - {2.731{DPR}_{1}} + {0.09734{DPR}_{1}^{2}}}{1 - {0.1124{DPR}_{1}} + {0.005045{DPR}_{1}^{2}}}{\quad{{\left\lbrack \frac{\left( {{Ra} - 1} \right)\left( {{Ra} - 2} \right)\left( {{Ra} - 4} \right)\left( {{Ra} - 8} \right)\left( {{Ra} - 10} \right)\left( {{Ra} - 12} \right)}{\left( {6 - 1} \right)\left( {6 - 2} \right)\left( {6 - 4} \right)\left( {6 - 8} \right)\left( {6 - 10} \right)\left( {6 - 12} \right)} \right\rbrack E\; 8} = {\frac{25.98 + {11.26{DPR}_{1}} + {0.02201{DPR}_{1}^{2}} + {0.5231{DPR}_{1}^{3}}}{1 - {0.8557{DPR}_{1}} + {0.00887{DPR}_{1}^{2}} + {0.02049{DPR}_{1}^{3}} - {0.000002866{DPR}_{1}^{4}}} \times {\quad{{\left\lbrack \frac{\left( {{Ra} - 1} \right)\left( {{Ra} - 2} \right)\left( {{Ra} - 4} \right)\left( {{Ra} - 6} \right)\left( {{Ra} - 10} \right)\left( {{Ra} - 12} \right)}{\left( {8 - 1} \right)\left( {8 - 2} \right)\left( {8 - 4} \right)\left( {8 - 6} \right)\left( {8 - 10} \right)\left( {8 - 12} \right)} \right\rbrack E\; 10} = {\frac{20.75 - {3.371{DPR}_{1}} + {0.9026{DPR}_{1}^{2}} + {0.01277{DPR}_{1}^{3}}}{1 - {0.1514{DPR}_{1}} + {0.03173{DPR}_{1}^{2}} + {0.0003673{DPR}_{1}^{3}}}{\quad{{\left\lbrack \frac{\left( {{Ra} - 1} \right)\left( {{Ra} - 2} \right)\left( {{Ra} - 4} \right)\left( {{Ra} - 6} \right)\left( {{Ra} - 8} \right)\left( {{Ra} - 12} \right)}{\left( {10 - 1} \right)\left( {10 - 2} \right)\left( {10 - 4} \right)\left( {10 - 6} \right)\left( {10 - 8} \right)\left( {10 - 12} \right)} \right\rbrack E\; 12} = {\frac{51.67 + {18.94{DPR}_{1}} + {21.57{DPR}_{1}^{2}} + {21.57{DPR}_{1}^{3}}}{1 + {1.183{DPR}_{1}} + {0.5513{DPR}_{1}^{2}} - {0.00004359{DPR}_{1}^{3}}}{\quad\left\lbrack \frac{\left( {{Ra} - 1} \right)\left( {{Ra} - 2} \right)\left( {{Ra} - 4} \right)\left( {{Ra} - 6} \right)\left( {{Ra} - 8} \right)\left( {{Ra} - 10} \right)}{\left( {12 - 1} \right)\left( {12 - 2} \right)\left( {12 - 4} \right)\left( {12 - 6} \right)\left( {12 - 8} \right)\left( {12 - 10} \right)} \right\rbrack}}}}}}}}}}}}}}}}}}$

and where Ra ranges from 1 to 12, and DPR₁ is greater than 0 and lessthan 300.

Preferably, Q₂≦18% if DPR₁<1; Q₂≦16.5% if 1≦DPR₁<3; Q₂≦15% if 3≦DPR₁<5;Q₂≦10% if 5≦DPR₁<10; Q₂≦7% if 10≦DPR₁<15; Q₂≦6% if 15≦DPR₁<20; Q₂≦4% if20≦DPR₁<30; Q₂≦3% if 30≦DPR₁<50; Q₂≦2% if 50≦DPR₁<100; and Q₂≦1% if100≦DPR₁<200. In preferred embodiments the fluid is passed into themanifold with a momentum (Mo) of at least 0.05.

In another aspect, the invention provides a louvered fluid processingdevice, comprising: an inlet to a chamber; a louver disposed within achamber; and an outlet from the chamber. A louver is a movable flowdirector. An example is illustrated in FIG. 34B. Preferably, there areat least two louvers in the chamber that are connected to rotatesimultaneously. Other options include: at least 3 coplanar inlets;further comprising a second chamber that is stacked adjacent to thechamber, wherein the first chamber comprises a heat exchanger. In onepreferred method involving the two chamber process, flows aresubstantially perpendicular to flow through the heat exchanger biased tofront of second (reaction) chamber. In some embodiments, the chamber hasheight of 5 micrometers or less.

In another aspect, the invention provides fluid processing apparatuscomprising: a manifold; a connecting channel matrix; and a movableorifice plate disposed between the manifold and the matrix, wherein themovable orifice plate has orifices of varying sizes that are alignedwith channels in the connecting channel matrix. An example isillustrated in FIG. 39. In a preferred embodiment, the movable orificeplate is held in place by screws. In some embodiments the movable platehas orifices that increase monotonically in size along the length of theplate. As in many of the other aspects, in some preferred embodiments,channels in the connecting channel matrix have the same cross-sectionalarea. The invention also provides a method of modifying a fluidprocessing apparatus comprising moving the position of a movable orificeplate in the above-described apparatus.

In another aspect, the invention provides a method of distributing flowfrom a manifold through a connecting channel matrix, comprising: passinga fluid through a manifold and into a connecting channel matrix, whereinthe connecting channel matrix comprises repeating units of microchannelsof differing cross-sectional areas, and wherein the manifold has aninlet disposed on one side of the connecting channel matrix so thatfluid flow through the manifold is at a nonzero angle to flow in theconnecting channel matrix; wherein the connecting channels in two ormore repeating units do not change in cross-sectional area in thedirection of length through the manifold; and wherein a fluid flows intothe manifold with a momentum (Mo) of at least 0.05; and is distributedthrough the connecting channel matrix with a Q₂ of less than 30%,preferably Q₂ is less than 25%, and more preferably less than 10%.“Repeating units” are a coplanar set of adjacent channels of differingcross-sectional areas that repeat. For example, a first channel having across-sectional area of 1 um² adjacent to a second channel having across-sectional area of 2 um² which is, in turn, adjacent to a thirdchannel having a cross-sectional area of 3 um²; This sequence repeatedthree times: 1:2:3/1:2:3/1:2:3 would be three repeating units. In someembodiments, the manifold is substantially perpendicular to theconnecting channels.

In method another aspect, the invention provides a method ofdistributing flow from a manifold through a connecting channel matrix,comprising: passing a fluid through a manifold inlet and into a manifoldsuch that the fluid passes through a first portion of a manifold in afirst flow regime and passes through a second portion of a manifold in asecond flow regime; wherein the manifold has a height of the manifold(h_(m2m)) of 2 mm or less and a length of an optional straighteningchannel portion (L₂) divided by L_(m2m) of less than 6. In this method,the DPR₂ ratio remains at 2 or greater or the DPR₃ ratio remains at 0.9or less. In this method, the fluid from the manifold is distributed intoat least two connecting channels, which are connected to the manifold,with a quality index factor as a function of connecting channel areas ofequal to or less than Q(Ra), where

Q(Ra)=0.0008135Ra ⁶−0.03114Ra ⁵+0.4519Ra ⁴−3.12Ra ³+11.22Ra²−23.9Ra+39.09.

In a preferred embodiment, the first flow regime is turbulent and secondflow regime is transitional. Preferably, R_(a) is equal to or less than12. In some embodiments, the fluid passes through a macromanifold andthen passes through the manifold inlet.

In another aspect, the invention provides a method of passing a fluidthrough a manifold of a microchannel device, comprising: flowing a firstfluid stream into a manifold and then through a first channel in a firstdirection; flowing a portion of the first fluid stream to a secondchannel; and flowing a portion of the first fluid stream through thesecond channel. In this method, the second channel extends at a nonzeroangle relative to the first direction; the second channel comprises amicrochannel and comprises at least one dividing wall that separates thesecond channel into at least a first and a second subchannel; the firstlayer and the manifold are each substantially planar; wherein themanifold is substantially contained within the first layer, and whereinthe first layer and the manifold are substantially coplanar, and thefirst channel is disposed in the first layer and flow through the firstchannel is substantially parallel to the plane of the first layer; thefirst channel and the manifold are about the same height; the secondlayer is substantially planar, the second channel is disposed in thesecond layer and flow through the second channel is substantiallyparallel to the plane of the second layer; and the first layer and thesecond layer are substantially parallel and the nonzero angle refers toan angle within the second layer. One embodiment of a structure throughwhich this method can be conducted is illustrated in FIG. 26 a. In apreferred embodiment, the second layer is adjacent (i.e., no interveninglayers) to the first layer and the only flow into the second layer isfrom the first layer. In another preferred embodiment, a platecomprising an opening is disposed between the first and second layersand flow from the first layer passes through the opening into the secondlayer. In another preferred embodiment, the first layer includesmultiple adjacent parallel microchannels which are separated by channelwalls; and the second layer comprises multiple adjacent parallelmicrochannels separated by continuous channel walls wherein thecontinuous channel walls traverse the width of the multiple adjacentparallel microchannels in the first layer. The second layer can be madefrom a sheet containing slots. In another embodiment, the first layercomprises multiple adjacent parallel microchannels separated by channelwalls; and the second layer comprises multiple adjacent parallelmicrochannels separated by continuous channel walls; and a portion ofthe flow through the first layer passes into the second layer where itis redistributed into the microchannels in the first layer. In anotherpreferred embodiment, the presence of the second layer tends to equalizeflow through the multiple adjacent parallel microchannels in the firstlayer; this means that there is a lower Q than if not present; (as withany of the other methods, Q could be any of the preferred Qs describedherein. In yet another embodiment of this method, the multiple adjacentparallel microchannels comprise a crossbar that forces flow into thesecond layer; and, other than contact with the first layer, the secondlayer does not have any inlets or outlets (an example is illustrated inFIG. 27). As with the any of the other methods, the invention includesthe apparatus of this method.

In another aspect the invention provides a system (and correspondingmethods utilizing the system) in which a macromanifold connects two ormore microdevices, where each microdevice has an M2M as describedherein. A “macromanifold” is a manifold that connects to at least twosmaller manifolds. For example, a macromanifold can be a pipe (outsideof a microchannel device) that connects to two or more M2M manifoldsthat are within a microchannel device. These systems, may include, forexample, one macro pipe or duct to two or more devices with M2M regions,then to two or more submanifolds in each device, then optionally to twoor more connecting channels from each submanifold. Another example of asystem includes, for example, a macropipe or duct, connected to two ormore devices with M2M regions, then to two or more submanifolds, thenfinally to two or more connecting channels, or one device including anM2M, to two or more submanifolds, then to two or more connectingchannels, then to subchannels within the connecting channels created bya fin structure.

In another aspect, the invention provides a method of passing a fluidthrough the manifold of a microchannel fluid processing device,comprising: passing a first fluid through a first inlet into a firstmanifold zone; passing a second fluid through a second inlet into asecond manifold zone; wherein a wall is disposed between the first andsecond manifold zones, and wherein the wall comprises openings thatpermit mixing of the first and second fluids in the manifold; whereinthe manifold is adjacent to a connecting channel matrix; forming a mixedfluid by combining the first and second fluids in the manifold; andwherein the mixed fluid passes into the connecting channel matrix. Anexample of this aspect is illustrated in FIG. 28.

In a further aspect, (see FIGS. 29 and 30) the invention provides amicrochannel fluid processing device, comprising: a manifold connectedto a connecting channel matrix; wherein the manifold and connectingchannel matrix are coplanar; and further comprising a flow directingfeature that comprises: an inclined manifold; or angled connections thatconnect the manifold and the connecting channel matrix. The angledconnections, if present, comprise angles in the range from 10 to 80, or100 to 170 degrees, relative to the central axis through the manifold.In a preferred embodiment, the angled connections that connect themanifold and the connecting channel matrix comprise angles in the rangefrom 10 to 80 in the first half of the length of the manifold, and 100to 170 degrees in the second half of the length of the manifold,relative to the central axis through the manifold. In cases in which themanifold is inclined, a preferred embodiment has the manifold inclinedso that manifold volume decreases with increasing length away from amanifold inlet. In some embodiments, these features are etched into asubstrate.

In another aspect, the invention provides a microchannel device,comprising: a manifold; a connecting channel matrix; at least threeorifice plates disposed in the manifold such that flow through theentire manifold would pass through all of said at least three orificeplates. In this device the at least three orifice plates have orificeswith differing cross-sectional areas; and the orifice plates divide themanifold into segments, wherein each segment is connected to at leastone connecting channel in a connecting channel matrix. An example isillustrated in FIG. 38. In a preferred embodiment, the orifice area inthe three plates decrease with increasing length down the manifold. Inanother embodiment, there are at least 3 connecting channels in eachsegment. Other preferred embodiments comprise grates and/or gates.

For any of the apparatus and methods, the heights of connecting channelsand/or manifolds are preferably in the range of 20 um to 5 mm, morepreferably 2 mm or less. The thickness of walls separating channels ormanifold walls are preferably in the range of 20 um to 5 mm, morepreferably 2 mm or less. Connecting channels preferably have a length of1 cm to 10 m. In a stacked device, the web thickness between layers ispreferably the thickness of a sheet (in other words, in some preferredembodiments, devices are made by cutting features through a sheet ratherthan etching). Throughout all aspects, the figures are merelyillustrative and do not limit all aspects of the invention). In manypreferred embodiments, the connecting channels are substantiallyparallel to the manifold to which the channels are connected.

According to the inventive methods, desired flow distributions can beachieved in microdevices containing multiple connecting channels fed bya manifold (or single connecting channels fed from a very highconnecting channel aspect ratio manifold); and these desired flowdistributions can be obtained even in high momentum conditions. Inpreferred methods of the invention, the momentum number, Mo, ispreferably at least 0.1, more preferably at least 0.2, in someembodiments, at least 0.5 and in some embodiments at least 5. In somepreferred embodiments, the manifold has an M2M manifold aspect ratio(defined below) of at least 10, or at least 20, or 50, or at least 100,and in some embodiments in the range of 30 to 1000. In preferredembodiments, FA (defined below) is 0.01 or less and more preferably lessthan 0.001. In some of the inventive methods, flow through the majority(by volumetric flow) of the connecting channels has a Reynolds number of10,000 or less, 5000 or less, 2000 or less, 1000 or less, and in someembodiments, in the range of 500 to 5000. In some preferred embodiments,at least two, more preferably at least 5, in some embodiments at least10 or at least 100 or, in some embodiments, 5 to 500 connecting channelsare served by a single M2M manifold. In many preferred embodiments, flowis controlled to be distributed equally over multiple connectingchannels with Q factors (as described below) of 30% or less, morepreferably 20% or less, and in some embodiments, in the range of 0.1% to15%.

Many of the inventions described herein have examples of flow from aheader manifold to manifold connections and connecting channels, butthat doesn't limit their application to the header. If the inventiondescription for flow from manifold interfaces to connecting channel oris used for a manifold to single connection channel interface, it can beused for analogous and reversed flow direction in the footer unlessexplicitly stated.

In some preferred embodiments, the laminated devices are chemicalreactors that are capable of processing fluid streams. The inventionalso includes devices having any of the structural features or designsdescribed herein. For example, the invention includes a device havingexothermic reaction channels in an interleaved relationship with coolantand/or endothermic reaction channels; and having one or more flowmodifiers in the reaction channels and/or being comprised ofsubassemblies at right angles to each other. In preferred embodiments,aspects of the invention are combined; for example, any of the catalystsdescribed herein may be selected to be incorporated into a reactionchannel in any of the laminate designs described herein.

For all of the methods of making devices that are described herein, theinvention also includes laminated devices made by the method. Theinvention also includes processes of conducting a unit operation (oroperations) using any of the devices, structural features, designs orsystems described herein.

The use of the fabrication techniques described herein can be applied toall devices for all chemical unit operations, including chemicalreactors, combustors, separators, heat exchangers, vaporizers,evaporators, and mixers. The applications may include both gaseous andliquid fluid processing or combinations of the two phases. Liquid fluidprocessing may also include the generation of suspended solids incontinuous liquid fluid phases, such as the formation of an emulsion.

Any of the articles described herein may have multiple layers andrepeating sets of layers (repeating units). For example, 2, 10, 50 ormore repeating units within a laminate. This multiplicity, or “numberingup” of layers creates added capacity of microchannel laminated devices.

Various embodiments of the present invention may possess advantages suchas: lower costs, more equal flow distribution in a multichannel array,lower manifold pressure drop, or additional heat transfer.

GLOSSARY

As is standard patent terminology, “comprising” means “including” andneither of these terms exclude the presence of additional or pluralcomponents. For example, where a device comprises a lamina, a sheet,etc., it should be understood that the inventive device may includemultiple laminae, sheets, etc.

The “channel axis” is the line through the center of a channelscross-section as it extends through the channel.

“Bonding” means attaching or adhering, and includes diffusion bonding,gluing, brazing and welding.

A “bump” is an obstruction or area of increased channel wall roughnessthat reduces mass flow rate through a channel under typical operatingconditions.

Capacity of a manifold, C_(man), is defined as the mass processed perunit volume of manifold:

$\begin{matrix}{C_{man} = \frac{m_{man}}{V_{man}}} & (1)\end{matrix}$

wherem_(man) [kg/sec]=Mass flow rate for a manifoldV_(man) [m³]=The total volume of the manifold: the manifold channels;internal distribution features, such as sub-manifolds and gates, gratesand other manifold connection channels, including their containmentwalls; the external containment walls of the manifold, including spacebetween manifold channels not used for other manifolds or processingchannels. The total volume of the manifold does not include the channelwalls in the layers directly above or below the manifold channel. Theexternal containment wall volume in an M2M manifold includes that volumethat separates the manifold from the necessary device perimeter of amicrochannel device, which occurs around the entire device. It includesthe wall volume separating the channels of fractal distributionmanifolds that aren't used by other connecting channels.

For microchannel devices with M2M manifolds within the stacked shimarchitecture, the M2M manifolds add to the overall volume of the deviceand so it is desirable to maximize the capacity of the manifold. Inpreferred embodiments of the invention, an M2M distributes 1 kg/m³/s,preferably 10 kg/m³/s, and in some preferred embodiments distributes 30to 150 kg/m³/s.

The connections between the manifold and the connecting channels (i.e.,the M2M distribution structures) described herein preferably havethicknesses (i.e., heights) of 20 um to 5 mm, more preferably 2 mm orless, and preferably have widths in the range of 100 um to 5 cm and insome preferred embodiments have widths more than 250 micrometers andless than one millimeter. The lengths of the connecting channels have alower limit of zero and an upper limit of 1 meter, and in some preferredembodiments a range of 2 millimeters to 10 cm.

The cross-sectional area of a channel is that cross-sectional planenormal to the channel axis. It excludes the cross-sectional area of thewall and any applied coatings (catalyst, bonding, metal protection) tothe wall. A layer typically includes plural channels that are separatedby channel walls. The cross-sectional area of a channel includes areataken up by catalyst, if present.

Channels are defined by channel walls that may be continuous or maycontain gaps. Interconnecting pathways through a monolith foam or feltare not connecting channels (although a foam, etc. may be disposedwithin a channel).

“Connecting channels” are channels connected to a manifold. Typically,unit operations occur in connecting channels. Connecting channels havean entrance cross-sectional plane and an exit cross-sectional plane.Although some unit operations or portions of unit operations may occurin a manifold, in preferred embodiments, greater than 70% (in someembodiments at least 95%) of a unit operation occurs in connectingchannels. A “connecting channel matrix” is a group of adjacent,substantially parallel connecting channels. In preferred embodiments,the connecting channel walls are straight.

The “connection to manifold cross-sectional area ratio” is the ratio ofthe cross-sectional area of open area of the manifold connection (suchas a gate or grate) to the cross-sectional area (perpendicular to thecentral axis) of the manifold at the position immediately upstream ofthe connection (for a header) or immediately downstream of a connection(for a footer).

The connecting channel pressure drop (ΔP_(CCdP)) is the static pressuredifference between the center of the entrance cross-sectional plane andthe center of the exit cross-sectional plane of the connecting channels.In some preferred embodiments, connecting channels are straight withsubstantially no variation in direction or width. The connecting channelpressure drop for a system of multiple connecting channels is thearithmetic mean of each individual connecting channel pressure drop.That is, the sum of the pressure drops through each channel divided bythe number of channels. For the examples, pressure drops are unadjusted;however, in the claims, pressure are defined based on the channels thatcomprise 95% of the net flow through the connecting channels, the lowestflow channels are not counted if the flow through those channels is notneeded to account for 95% of the net flow.

The FA dimensionless number is a means of distinguishing high momentumflow from creeping flow in manifolds:

$\begin{matrix}{{FA} = {\frac{\left\lbrack {0.058 + {0.0023\left( {\ln \; {Re}} \right)^{2}}} \right\rbrack^{2}D}{L_{M\; 2M}} < 0.01}} & (2)\end{matrix}$

where Re is the manifold Reynolds number, D is the manifold hydraulicdiameter and L_(M2M) is the manifold zone length. The header manifoldReynolds number and hydraulic diameter for FA are defined at theposition on the channel axis where the wall plane closest to the headerentrance belonging to the connecting channel closest to the entrance inthe manifold connects with the channel axis. The footer manifoldReynolds number and hydraulic diameter for FA are defined at theposition where the wall plane closest to the footer exit belonging tothe connecting channel closest to footer exit connects with the channelaxis. FA should be below 0.01 and for some preferred embodiments lessthan 0.001.

A “flow resistor” is a bump, grate, or porous body. A flow resistor isnot a simple straight channel, and is not a gate at the start of achannel.

A “footer” is a manifold arranged to take away fluid from connectingchannels.

A “gate” comprises an interface between the manifold and two or moreconnecting channels. A gate has a nonzero volume. A gate controls flowinto multiple connecting channels by varying the cross sectional area ofthe entrance to the connecting channels. A gate is distinct from asimple orifice, in that the fluid flowing through a gate has positivemomentum in both the direction of the flow in the manifold and thedirection of flow in the connecting channel as it passes through thegate. In contrast, greater than 75% of the positive momentum vector offlow through an orifice is in the direction of the orifice's axis. Atypical ratio of the cross sectional area of flow through a gate rangesbetween 2-98% (and in some embodiments 5% to 52%) of the cross sectionalarea of the connecting channels controlled by the gate including thecross sectional area of the walls between the connecting channelscontrolled by the gate. The use of two or more gates allows use of themanifold interface's cross sectional area as a means of tailoringmanifold turning losses, which in turn enables equal flow rates betweenthe gates. These gate turning losses can be used to compensate for thechanges in the manifold pressure profiles caused by friction pressurelosses and momentum compensation, both of which have an effect upon themanifold pressure profile. The maximum variation in the cross-sectionalarea divided by the minimum area, given by the Ra number, is preferablyless than 8, more preferably less than 6 and in even more preferredembodiments less than 4. In a preferred shim construction (shown inFIGS. 3E and 3F), a gate comprises two or more adjoining shims that havechannel walls 32′ connected at their respective ends. These end wallconnections 34′ fix the channel walls in space so that the ends do notmove during manufacturing and handling. At least one shim has end wallconnections continuous across the width of the gate's two or moreconnecting channels and walls to form the perimeter edge of the manifold34′. The end wall connection in this shim creates a barrier for fluidflow between the manifold 36 and the two or more connecting channels35′. The illustrated shim also has an intermediate wall connection 37′between the connecting channels and the end wall connections. The planeextending in the stacking direction from wall 37′ is the connectingchannel plane exit or entrance. The intermediate wall connection acts asa barrier for flow between the gate's two or more connecting channels,leaving an open volume between connections for flow distribution in theconnection 38′. At least one other shim (the gate opening′ shim) has,where it interfaces the manifold perimeter, the end wall connection 42′only partially continuous across the width of the gate's two or moreconnecting channels and walls. There is one continuous section 44′ ofthe end wall channel that is offset from the manifold perimeter,extending from the manifold 36′ far enough to allow a flow to travelpast the barrier created by the continuous end wall connections. Thewalls 44′ and 34′ form a connection 46′ between the manifold and theconnecting channels. The plane extending in the stacking direction fromwall 34′ is the manifold interface plane. Two or more connectingchannels in the “gate opening” shim provide a flow connection 46′ intothe connecting channels.

In some preferred embodiments, connecting channels are aligned inadjacent shims (such as in region 47′ of FIG. 3E)

A “grate” is a connection between a manifold and a single channel. Agrate has a nonzero connection volume. In a shim construction (shown inFIG. 3D), a grate is formed when a cross bar in a first shim is notaligned with a cross bar in an adjacent second shim such that flowpasses over the cross bar in the first shim and under the cross bar inthe second shim.

The “head” refers to the dynamic head of a channel flow, defined by thefollowing equation

$\begin{matrix}{{{head} = {\frac{\rho \; U^{2}}{2} = \frac{G^{2}}{2\rho}}},} & (3)\end{matrix}$

whereρ [kg/m³]=density of the fluidG [kg/m²/s]=mass flux rate of the fluidU [m/s]=specific velocity of the fluidThe head is defined at the position of interest.

A “header” is a manifold arranged to deliver fluid to connectingchannels.

A “height” is a direction perpendicular to length. In a laminateddevice, height is the stacking direction. See also FIG. 1A.

A “hydraulic diameter” of a channel is defined as four times thecross-sectional area of the channel divided by the length of thechannel's wetted perimeter.

An “L-manifold” describes a manifold design where flow direction intoone manifold is normal to axes of the connecting channel, while the flowdirection in the opposite manifold is parallel with the axes of theconnecting channels. For example, a header L-manifold has a manifoldflow normal to the axes of the connecting channels, while the footermanifold flow travels in the direction of connecting channels axes outof the device. The flow makes an “L” turn from the manifold inlet,through the connecting channels, and out of the device. When twoL-manifolds are brought together to serve a connecting channel matrix,where the header has inlets on both ends of the manifold or a footer hasexits from both ends of the manifold, the manifold is called a“T-manifold”.

A “laminated device” is a device made from laminae that is capable ofperforming a unit operation on a process stream that flows through thedevice.

A “length” refers to the distance in the direction of a channels (ormanifolds) axis, which is in the direction of flow.

“M2M manifold” is defined as a macro-to-micro manifold, that is, amicrochannel manifold that distributes flow to or from one or moreconnecting microchannels. The M2M manifold in turn takes flow to or fromanother larger cross-sectional area delivery source, also known as macromanifold. The macro manifold can be, for example, a pipe, a duct or anopen reservoir.

A “macromanifold” is a pipe, tube, or duct that connects multiplemicrodevices to a single inlet and/or outlet. Flow in the macromanifoldis in either the transition or turbulent regime. Each microdevicefurther comprises a manifold for distributing flow to multiple parallelmicrochannels (i.e., a connecting channel matrix).

A “manifold” is a volume that distributes flow to two or more connectingchannels or to a very large aspect ratio (aspect ratios ≧30:1) singleconnecting channel. Aspect ratio is defined as the width of the channel(the flow direction through the volume) over its height in the stackingdirection. The entrance, or inlet, plane of a header manifold is definedas the plane in which marks a significant difference in header manifoldgeometry from the upstream channel. The header manifold includes anyvolume between the entrance plane and the L_(M2M) header beginningpoint. The exit, or outlet, plane of the footer manifold is defined asthe plane which marks a significant difference in the footer manifoldchannel from the downstream channel. A significant difference inmanifold geometry will be accompanied by a significant difference inflow direction and/or mass flux rate. A manifold includes submanifoldsif the submanifolding does not cause significant difference in flowdirection and/or mass flux rate. The footer manifold includes any volumebetween the L_(M2M) footer end point and the exit plane. For example, amicrochannel header manifolds entrance plane is the plane where themicrochannel header interfaces a larger delivery header manifold, suchas a pipe or duct, attached to the microchannel device through welding aflange or other joining methods. Similarly, a header manifold starts atthe plane where a tub-like, non-microchannel header connects with amicrochannel header space. In most cases, a person skilled in this artwill readily recognize the boundaries of a manifold that serves a groupof connecting channels.

A “manifold connection” is the plane between the manifold and one ormore connecting channels. The manifold connection plane can have avolume associated with it for a single connecting channel, and must havea volume if connected through a gate to two or more channels.

A “manifold length” (L_(M2M)) is the length of the manifold over itsconnecting channels. For a header, L_(M2M) is the distance between wherethe wall plane closest to the header entrance belonging to theconnecting channel closest to the header entrance connects with themanifold channel axis, the “L_(M2M) header beginning point”, and theposition where the wall plane farthest away from the header entrancebelonging to the connecting channel farthest away from the headerentrance connects with the manifold channel axis, the “L_(M2M) headerend point”. For a header T-manifolds and header U-manifolds, the L_(M2M)header end point is the midpoint on the line between the two oppositeL_(M2M) header beginning points if the channel has a constantcross-sectional area and the L_(M2M) header end point is where the twosides's manifold channel axis lines cross, assuming symmetry between thetwo manifold sides. For a footer, the L_(M2M) is the distance betweenthe position where the wall plane farthest away from the footer exitbelonging to the connecting channel farthest away from the footer exitconnects with the channel axis, the “L_(M2M) footer beginning point”,and the position where the wall plane closest to the footer exitbelonging to the connecting channel closest to the footer exit connectswith the channel axis, the “L_(M2M) footer end point”. For a headerT-manifolds and header U-manifolds, the L_(M2M) header end point is themidpoint on the line between the two opposite L_(M2M) header beginningpoints if the channel has a constant cross-sectional area and theL_(M2M) header end point is where the two sides's manifold channel axislines cross, assuming symmetry between the two manifold sides. Anexample of L_(M2M) is seen in FIG. 1A.

For a header the “manifold pressure drop” (ΔP_(manifold)) is the staticpressure difference between the arithmetic mean of the area-averagedcenter pressures of the header manifold inlet planes (in the case wherethere is only one header inlet, there is only one inlet plane) and thearithmetic mean of each of the connecting channels' entrance planecenter pressures. The header manifold pressure drop is based on theheader manifold entrance planes that comprise 95% of the net flowthrough the connecting channels, the header manifold inlet planes havingthe lowest flow are not counted in the arithmetic mean if the flowthrough those header manifold inlet planes is not needed to account for95% of the net flow through the connecting channels. The header (orfooter) manifold pressure drop is also based only on the connectingchannels' entrance (or exit) plane center pressures that comprise 95% ofthe net flow through the connecting channels, the connecting channels'entrance (or exit) planes having the lowest flow are not counted in thearithmetic mean if the flow through those connecting channels is notneeded to account for 95% of the net flow through the connectingchannels. For a footer, the manifold pressure drop is the staticpressure difference between the arithmetic mean of each of theconnecting channers exit plane center pressures and the arithmetic meanof the area-averaged center pressures of the footer manifold outletplanes (in the case where there is only one header outlet, there is onlyone outlet plane). The footer manifold pressure drop is based on thefooter manifold exit planes that comprise 95% of the net flow throughthe connecting channels, the footer manifold outlet planes with thelowest flow are not counted in the arithmetic mean if the flow throughthose exit planes is not needed to account for 95% of the net flowthrough the connecting channels.

For a header manifold the “manifold to interface pressure drop”(ΔP_(M2I)) is the static pressure difference between the point of the“header manifold pressure at the interface”, where the header manifoldchannel axis crosses the plane that bisects the manifold connectionwidth through the manifold connection channel axis, where that planegoes through the bottom and top of the manifold connection channel inthe stacking direction, and the center of the connecting channel inletplane or the arithmetic mean of the connecting channel plane centersconnected to the manifold connection. For a footer manifold the manifoldto interface pressure (i.e., the “footer manifold pressure at theinterface”) is defined as the absolute value of the pressure differencebetween the arithmetic mean of the connecting channel's exit planecenter pressures and the point where the footer manifold channel axiscrosses the plane that bisects the manifold connection width through themanifold connection axis, where that plane goes through the bottom andtop of the manifold connection channel in the height (stacking forlaminated device) direction. Examples of the manifold connection includea grate, a gate or orifices. The manifold connection can only be theentrance or exit of a connecting channel if the manifold connection is aplane between the connection and the manifold.

The mass flux rate G is the mass flow rate per unit cross-sectional areaof the channel in the direction of the channers axis.

A “microchannel” has at least one internal dimension of 5 mm or less. Amicrochannel has dimensions of height, width and length. The heightand/or width is preferably about 5 mm or less, and more preferably 2 mmor less. The length is typically longer. Preferably, the length isgreater than 1 cm, more preferably in the range of 1 cm to 5 m. Amicrochannel can vary in cross-section along its length, but amicrochannel is not merely an orifice such as an inlet orifice.

The ratio of the manifolds head to its friction loss, Mo, is defined bythe following equation:

$\begin{matrix}{{Mo} = {\frac{\frac{1}{2\rho}\left\lbrack {G^{2} - 0} \right\rbrack}{\frac{4{fL}_{M\; 2M}}{D}\frac{G^{2}}{2\rho}} = \left\{ \frac{4{fL}_{M\; 2M}}{D} \right\}^{- 1}}} & (4)\end{matrix}$

where,D [m]=manifold hydraulic diameter at the M2M reference pointf [dimensionless]=Fanning friction factor for the M2M reference pointG [kg/m²/s]=mass flux rate at the M2M reference pointThe reference point of header manifold Reynolds number and hydraulicdiameter for Mo are defined at the position on the channel axis wherethe wall plane closest to the header entrance belonging to theconnecting channel closest to the entrance in the manifold connects withthe channel axis. The footer manifold Reynolds number and hydraulicdiameter for Mo are defined at the reference point at the position wherethe wall plane closest to the footer exit belonging to the connectingchannel closest to footer exit connects with the channel axis.

A module is a large capacity microchannel device, made up of multiplelayers of repeating unit combinations.

An “open channel” is a gap of at least 0.05 mm that extends all the waythrough a microchannel such that fluids can flow through themicrochannel with relatively low pressure drop.

The “pressure drop ratio #1” (PDR₁) is defined as the ratio ofconnecting channel pressure drop over the representative head of themanifold (the L_(M2M) header beginning point “for a header, the L_(M2M)footer end point” for the footer):

$\begin{matrix}{{DPR}_{1} = {\frac{\Delta \; P_{CCdP}}{h} = \frac{{\Delta P}_{CCdP}}{\frac{G^{2}}{2\rho}}}} & (5)\end{matrix}$

If a manifold has more than one sub-manifold, the head is based upon thearithmetic (number average) mean of the individual sub-manifold G and ρvalues.

The “pressure drop ratio #2” (PDR₂) is defined as the ratio ofconnecting channel pressure drop over the manifold pressure drop:

$\begin{matrix}{{DPR}_{2} = \frac{\Delta \; P_{CCdP}}{\Delta \; P_{manifold}}} & (6)\end{matrix}$

If a manifold has more than one sub-manifold, the manifold pressure dropis based upon the number average of sub-manifold values.

The “pressure drop ratio #3” (DPR₃) is defined as the ratio of manifoldto interface pressure drop over the manifold pressure drop,

$\begin{matrix}{{DPR}_{3} = \frac{\Delta \; P_{M\; 2I}}{\Delta \; P_{manifold}}} & (7)\end{matrix}$

In preferred embodiments, the arithmetic mean of DPR₃ for a manifold isless than 0.9, based on the manifold connections that comprise 95% ofthe net flow through the connecting channels, the lowest flow manifoldconnections are not counted if the flow through those channels is notneeded to account for 95% of the net flow through the connectingchannels. More preferable embodiments have DPR₃ values based on the samecriteria of less than 0.75, more preferably less than 0.50, morepreferably still 0.25 and most preferably less than 0.10.

“Process channel volume” is the internal volume of a process (i.e.,connecting) channel. This volume includes the volume of the catalyst (ifpresent) and the open flow volume (if present). This volume does notinclude the channel walls. For example, a reaction chamber that iscomprised of a 2 cm×2 cm×0.1 cm catalyst and a 2 cm×2 cm×0.2 cm openvolume for flow immediately adjacent to the catalyst, would have a totalvolume of 1.2 cm³.

Quality Index factor “Q₁” is a measure of how effective a manifold is indistributing flow. It is the ratio of the difference between the maximumand minimum rate of connecting channel flow divided by the maximum rate.For systems of connecting channels with constant channel dimensions itis often desired to achieve equal mass flow rate per channel. Theequation for this case is shown below, and is defined as Q₁.

$\begin{matrix}{Q_{1} = {\frac{m_{\max} - \min_{\min}}{m_{\max}} \times 100\%}} & (8)\end{matrix}$

wherem_(max) [kg/sec]=maximum connecting channel mass flow ratem_(min) [kg/sec]=minimum connecting channel mass flow rateFor cases when there are varying connecting channel dimensions it isoften desired that the residence time, contact time, velocity or massflux rate have minimal variation from channel to channel such that therequired duty of the unit operation is attained. For those cases wedefine a quality index factor Q₂:

${Q_{2} = {\frac{G_{\max} - G_{\min}}{G_{\max}} \times 100\%}},$

where G is the mass flux rate. For cases when all the connectingchannels have the same cross sectional area, the equation for Q₂simplifies to Q₁. The quality index factor gives the range of connectingchannel flow rates, with 0% being perfect distribution, 100% showingstagnation (no flow) in at least one channel, and values of over 100%indicating backflow (flow in reverse of the desired flow direction) inat least one channel. For the examples, Q₁ and Q₂ are unadjusted;however, in the claims, Q₁ and Q₂ are defined based on the channels thatcomprise 95% of the net flow through the connecting channels, the lowestflow channels are not counted if the flow through those channels is notneeded to account for 95% of the net flow through the connectingchannels.

Ra (=A_(max)/A_(min)) is the cross-sectional area ratio of the biggestto the smallest connection between a manifold and connecting channels.These areas can belong to gates or grates.

The Reynolds number, Re, is the commonly used ratio of the inertial overthe viscous forces seen by flow in a channel. Its definition is theratio of the mass flux rate (G) times the hydraulic diameter (D) dividedby the dynamic viscosity (μ),

$\begin{matrix}{{Re} = {\frac{GD}{\mu} = \frac{\rho \; {UD}}{\mu}}} & (9)\end{matrix}$

The value of the Reynolds number describes the flow regime of thestream. While the dependence of the regime on Reynolds number is afunction of channel cross-section shape and size, the following rangesare typically used for channels:

Laminar: Re<2000 to 2200

Transition: 2000-2200<Re<4000 to 5000

Turbulent: Re>4000 to 5000

“Sheets” or “shims” refer to substantially planar plates or sheets thatcan have any width and length and preferably have a thickness (thesmallest dimension) of 5 millimeter (mm) or less, more preferably 0.080inch (2 mm) or less, and in some preferred embodiments between 50 and1000 μm. Width and length are mutually perpendicular and areperpendicular to thickness. In preferred embodiments, a sheet has lengthand width that are coextensive the length and width of the stack oflaminae in which the sheet resides. Length of a sheet is in thedirection of flow; however, in those cases in which the direction offlow cannot be determined, length is the longest dimension of a sheet.

A “subchannel” is a channel that is within a larger channel. Channelsand subchannels are defined along their length by channel walls.

A “sub-manifold” is a manifold that operates in conjunction with atleast one other submanifold to make one large manifold in a plane.Sub-manifolds are separated from each other by continuous walls.

“Thickness” is measured in the stacking direction.

In a “U-manifold,” fluid in a header and footer flow in oppositedirections while being at a non zero angle to the axes of the connectingchannels. When two U-manifolds are brought together to serve aconnecting channel matrix, with entrances on both open ends of theheader manifold and exits on both open ends of the footer, the manifoldis called an “I-manifold”.

“Unit operation” means chemical reaction, vaporization, compression,chemical separation, distillation, condensation, mixing, heating, orcooling. A “unit operation” does not mean merely fluid transport,although transport frequently occurs along with unit operations. In somepreferred embodiments, a unit operation is not merely mixing.

In a “Z-manifold,” fluid in a header and footer flow in the samedirection while being at a non zero angle to the axes of the connectingchannels. Fluid entering the manifold system exits from the oppositeside of the device from where it enters. The flow essentially makes a“Z” direction from inlet to outlet.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1A shows a three opening manifold with mass flux rates (G), staticpressures (P) and constant connection channel widths (W_(cc)).

FIG. 1B shows dimensions for a three opening header manifold.

FIG. 2A illustrates the static pressure profile in an M2M based onturbulent pipe turning loss and momentum compensation coefficients forthe Z-manifold. Channel #1 is the first channel seen in the header, #19the last channel seen by the footer. The diamonds show pressure in theheader and the squares show pressure drop in the footer.

FIG. 2B illustrates M2M header manifold momentum compensationcoefficients for an connection to manifold cross-sectional area ratio of0.09 for several M2M header manifold mass flow rate ratios (MFR), theratio of the mass flow rates downstream to upstream of a connectingchannel.

FIG. 2C illustrates experimentally obtained M2M header manifold turningloss coefficients versus the channel mass flow rate ratio (connectingchannel to manifold upstream of connecting channel) for a connection tomanifold cross-sectional area ratio of 0.09. Also plotted are the headermanifold turning loss coefficients for conventional turbulent circularpipes (solid line for the same connection to manifold cross-sectionalarea ratio).

FIG. 2D illustrates negative footer turning loss coefficients for aconnection to manifold cross-sectional area ratio of 0.09 inconventional pipes and an M2M manifold.

FIG. 3A illustrates a set of sub-manifolds for a Z-manifold system.

FIG. 3B illustrates a L-manifold system containing two submanifolds.

FIG. 3C illustrates an example of a grate for a stacked shim system withthe grate extending across the M2M manifold channels width.

FIG. 3D illustrates a grate design with a grate pulled into themanifold.

FIG. 3E illustrates a “Gate” design formed by an upper gate shim and alower channel shim. The gray (upper) shim makes the opening with the M2Mmanifold and the lower “picture frame” shim makes a plane fordistribution to the connecting channels, of which an example of four areshown here for each gate.

FIG. 3F illustrates the “Gate” design of FIG. 3E where the shims havebeen inverted across the major central plane.

FIG. 3G illustrates decreasing cross-sectional area of the gates in thedirection of flow.

FIGS. 4-22 illustrate shim designs that were assembled to construct andintegrated combustion reactor.

FIG. 23 illustrates a manifold used to separate phases.

FIG. 24 illustrates a manifold with gates of decreasing channel width inthe direction of manifold flow to obtain a more equal flow distribution.

FIG. 25 a illustrates a design with gates and submanifold zones.

FIG. 25 b illustrates a manifold with a straightening zone.

FIG. 25 c is an exploded view of the laminate of FIG. 25 b.

FIGS. 26 a, 26 b and 27 illustrate flow bumps in channels made by a shimconstruction.

FIG. 28 illustrates a cross flow manifold with openings for mixing.

FIG. 29 illustrates an inclined manifold.

FIG. 30 schematically illustrates angled openings between a manifold anda set of connecting channels.

FIG. 31 illustrates a channel design with offset regions forinterchannel mixing.

FIG. 32 illustrates a gate design in which porous bodies provide equalflow.

FIG. 33 illustrates a flexible wall projection that alters flow througha channel.

FIG. 34A schematically illustrates a macromanifold connected to twomicrodevices.

FIG. 34B illustrates a non-divergent header with convergent footer andmultiple inlets and outlets parallel the direction of flow. Louvers canbe used to direct flow.

FIG. 35 illustrates a central flow redistributed by a flow distributionplate.

FIG. 36 illustrates an exploded view schematic of a high-pressurevaporizer showing the center-fed inlet, the first and second plates anda two-dimensional channel array in orthogonal shims Flow is collected onthe opposite side of the channel array with a centrally located outletpipe, directly opposite the inlet pipe entrance.

FIG. 37 illustrates a manifold design with nonaligned orifice plates.

FIG. 38 is a cross-sectional, top down view of a device in which theheader contains orifice plates.

FIGS. 39A and 39B illustrate a cross-flow reactor utilizing a moveabledistribution plate.

FIG. 40 shows channel mass flux rates in connecting channels accordingto the analysis in comparative Example 1 using 10⁻⁰⁶ kg/s of air.

FIG. 41 shows channel mass flux rates in connecting channels accordingto the analysis in comparative Example 1 using 10⁻⁰⁶ kg/s of air at roomtemperature and pressure with developing flow and all momentum termsincluded.

FIG. 42 shows channel mass flux rates in connecting channels accordingto the analysis in comparative Example 1 using 10⁻⁰⁶ kg/s of water atroom temperature with developing flow and all the momentum termsincluded.

FIG. 43 shows channel mass flux rates in connecting channels accordingto the analysis in comparative Example 1 using 10⁻⁰⁶ kg/s of water withwider header and footer widths with developing flow and all momentumterms included.

FIG. 44 shows channel mass flux rates in connecting channels accordingto the analysis in comparative Example 1 using 10⁻⁰⁵ kg/sec (10× that ofFIG. 43) with wider header and footer widths with developing flow andall momentum terms included.

FIG. 45 shows predicted static gage pressures in an air M2M manifold forthe header and in the gate plotted versus fuel gate number from Example2. Air gate number 1 corresponds to air sub-manifold 1, gate 1, whilefuel gate number 18 corresponds to sub-manifold 6, gate 3.

FIG. 46 shows predicted static gage pressures in an fuel M2M manifoldfor the header and in the gate plotted versus fuel gate number fromExample 2. Fuel gate number 1 corresponds to fuel sub-manifold 1, gate1, while fuel gate number 18 corresponds to sub-manifold 6, gate 3.

FIG. 47 shows predicted channel mass flow rates for the air and fuelchannels plotted versus fuel channel number for Example 2. Fuel channel1 is channel 1 of sub-manifold 1 and fuel channel 72 is channel 12 ofsub-manifold 6.

FIG. 48 shows mass flow rate distribution for the air manifold testpiece of Example 3 plotted versus channel number. Channel 1 is closestto the manifold entrance while channel 12 is the farthest away.

FIG. 49 is a plot of static pressure as a function of distance of thechannel position from the submanifold entrance.

FIG. 50 illustrates channel flow distribution from Example 4 for a 2.00″wide M2M channel with M=0.160″, L=0.120″ and B=0.5.

FIG. 51 illustrates minimum quality index factors plotted versusconnecting channel to manifold pressure drop ratio (PDR₂) as explainedin Example 5.

FIG. 52 illustrates minimum quality index factors plotted versusconnecting channel to manifold pressure drop ratio (PDR₁) as explainedin Example 5.

DETAILED DESCRIPTION OF THE INVENTION Flow Distribution in a Plane

Discussion of Manifold Fluid Dynamics

This section will describe manifold physics important to manifold designand begin to describe how M2M manifolds differ from larger scalemanifold systems. The following section will describe experimentallyobtained M2M parameters relevant to the invention. Fried and Idelchik in“Flow resistance: A design guide for engineers,” Hemisphere PublishingCorporation, 1989, and Idelchik Dekker in “Fluid Dynamics of IndustrialEquipment: Flow distribution Design Methods”, Hemisphere PublishingCorporation, 1991 have described means of designing conventionally-sizedpipe and duct manifolds with large cross-sectional area connections.These ducts are characterized by large hydraulic diameters for themanifold and the connecting channels. Because of the large hydraulicdiameters even small specific velocities or mass flux rates can lead toturbulent Reynolds numbers that dominate the friction losses and theother manifold physics. In M2M manifolds, the manifold channels arebuilt into the layers of the device, so they often have hydraulicdiameters on the same order of the connecting channels, much smallerthan many conventional pipe or duct based manifold systems. Due to theM2M manifold having small hydraulic diameters, fairly large specificvelocities or mass flux rates can have transition and even laminar flowcharacteristics which can affect flow distribution in ways differentfrom fully turbulent manifolds.

In large pipe and duct manifolds the relative cross-sectional areas ofdelivery manifolds compared to the connecting channels are often limitedby the size of the delivery manifold. As the delivery manifoldshydraulic diameter is sized to lower the pressure drop of the system,its cross-sectional area is typically larger than the interface with theconnecting channel to make fabrication of the connection (welding,joining or flanging) easier. For this reason the connection to manifoldcross-sectional area ratio of the connecting channel interface to thedelivery manifold is equal to or less than one for most cases. For M2Mmanifolds, the connection from the manifold to the connecting channelsis fabricated in the same manner as the connecting channels, so thefabrication limitations of size of the connecting channel opening todelivery manifold is taken away. The in plane fabrication methods couldallow one or more connecting channels with a manifold interface that hasa larger area than the manifold, and its connection to manifoldcross-sectional area ratio could be larger than unity.

For large pipe and duct manifolds the effect of friction losses in thelength of the manifold directly adjacent to the connecting channelinterface is usually negligible because the length over hydraulicdiameter are on the order of unity (L/D˜1). Because of the small L/Dratio, one only accounts for momentum compensation, discussed later, inthat zone. As discussed in the previous paragraph, the length of the M2Mmanifolds adjacent to the connecting channel interfaces can be large dueto channel geometry resulting in length over diameter ratios much largerthan unity, so that one can't always assume that the friction losses canbe ignored.

To design a manifold for a set of connecting channels, it is useful touse one-dimensional coefficients to describe complex three-dimensionalflow resistances wherever possible, and this analysis will use equationssimilar to those used by Fried and Idelchik. Using one-dimensionalcoefficients allows a designer to solve for local momentum balances andmass continuity in a manner akin to electrical circuit analysis, whichis very useful when evaluating design changes for flow distribution. Byusing one-dimensional coefficients, the source of major flowmaldistributions can be identified and manifold physics compensated forin ways discussed later in the patent. To design using the circuitanalysis, the representative equations that need to be solved aredefined. This description will be illustrated using a case of threeconnecting channels, shown in FIG. 1. The channels have three manifoldconnecting areas, where the cross-sectional areas are A_(c,i) [m²]. Theconnecting channel cross sectional areas are A_(cc), [m²]. The localmass flux rates G [kg/m²/s] and the local, absolute static pressures P[Pa] are shown. A_(c,i) [m²] (can be a gate, or any other orificedesign), which may or may not be different than the channel area(A_(cc), [m²]). The cross-sectional area in the manifold can change inthe direction of flow, as shown in FIGS. 1A and 1B with changing width.

In many embodiments of the present invention, distribution is preferredto be equal, or nearly so, in all connecting channels. However, itshould be noted that a small amount of flow maldistribution may beacceptable and not noticeable from the overall device performance. Insome embodiments, the amount of acceptable flow maldistribution may beequivalent to a quality index factor of 5%, 10%, or up to 30%. By equal,is meant that one of the following conditions hold:

Constant mass flow rate, m [kg/s]: all connecting channels have the samecross-sectional area, A_(cc) [m²], as a design basis. This leads to a Q₁value of zero. This is the basis for the channels in FIGS. 1A and 1B.

Constant mass flux rate, G: for cases when the connecting channels havedifferent channel sectional areas, but the total contact time is thesame. This leads to a Q₂ value of zero.

For cases when all cross sectional areas are equal, the constant massflux rate simplifies to constant mass flow rate case.

For the design of the manifold and connecting channels, a set ofequations are solved to determine mass flux rates and pressures.

The momentum balance from the inlet to the outlet of connecting channeli in FIGS. 1A and 1B is

$\begin{matrix}{{\Delta \; P_{{cc},i}} = {{P_{i,c} - P_{i,o}} = {r_{cc}\frac{G_{c,i}^{2}}{2\; \rho}}}} & (10)\end{matrix}$

wherer_(cc) [-]=Connecting channel flow resistanceG_(c,i) [kg/m²/s]=Connecting channel is mass flux rate, based uponA_(cc).P_(i,c) [Pa]=Pressure of the header manifold connection plane centerP_(i,o) [Pa]=Pressure of the footer manifold connection plane centerΔP_(cc,i) [Pa]=Connecting channel i pressure differentialρ [kg/m³]=Density of fluidA resistance function representing several flow resistance terms may beused instead of a series of individual momentum balances for theconnecting channels, such as friction losses, cross-sectional areachanges and other losses. The resistance can be a function of mass fluxrate, geometry, molar composition changes, and temperature changes amongothers. Either resistance or a series of individual momentum balancescan be used, and resistance is used here to simplify the system. Aresistance function is obtained by taking the sum of the connectingchannel pressure drops for a range of flow rates and dividing eachpressure drop by its representative head value (G_(c,i) ²/2/ρ), thencorrelating by the head value.

To generate pressure drops in the connecting channels, the pressuredrops have to be calculated from known correlations or estimatedexperimentally. Friction pressure losses for straight sections ofconnecting channels can be calculated using the Fanning frictionfactors. Sources of Fanning friction factors and their manner of useinclude Rohsenow et al [“Handbook of Heat Transfer”, 3^(rd) ed. McGrawHill, 1998] for a wide range of channel geometries, and Shah and London[“Laminar Flow forced convection in ducts”, Supplement 1 to Advances inHeat Transfer, Academic Press, new York, 1978] for laminar flows. Careshould be placed in using appropriate Reynolds numbers, channel geometryfactors (such as aspect ratios), and hydrodynamic dimensionless lengths(x⁺=L/D/Re, where L is the section's length, D is channers hydraulicdiameter and Re is the channers Reynolds number) for laminar flows forthe Fanning friction factor. If friction factors aren't available forthe connecting channels considered, experimental values can be obtainedfrom fabricated channels fitted with pressure taps placed in welldeveloped flow zones. If the connecting channels have pressure dropsfrom sudden changes in cross-sections or changes in plane, Fried andIdelchik [“Flow resistance: A design guide for engineers,” HemispherePublishing Corporation, 1989] have a number of equations and references.

To set a perfect distribution, solving for the G_(c,i) then results in

$\begin{matrix}{G_{c,i} = {G_{c,{perf}} = \sqrt{2\; \rho \frac{\Delta \; P_{{cc},i}}{r_{cc}}}}} & (11)\end{matrix}$

G_(c,perf) [kg/m²/S]=Connecting channel perfect mass flux rate, i.e. thedesign point.If the fluid is incompressible, the fluid density is an average of theconnecting channel conditions. If the fluid is an ideal gas and theconnecting channel pressure drop is less than 10% of the inlet pressure,the density can be approximated by the local average pressure,temperature and molecular weight of the gas as follows

$\begin{matrix}{G_{c,i} = {G_{c,{perf}} = \sqrt{\frac{P_{i,c}^{2} - P_{i,o}^{2}}{r_{cc}}\left( \frac{{Mw}_{e}}{{RT}_{e}} \right)}}} & (12)\end{matrix}$

where we use an equivalent set of parameters to describe changingconnecting channel conditions:Mw_(e) [kg/gm-mole]=Average mole fraction for the gas in the connectingchannelR [J/gm-mole/K]=Gas constantT_(e) [K]=Average gas temperatureThe following six factors characterize the system:

-   -   1. The outlet pressure profile, P_(i,o) for i from 1 to N total        channels    -   2. Either one of the following:        -   a. The inlet pressure of the macro manifold, P_(macro)        -   b. Or the inlet pressure of the M2M manifold, P_(in)        -   c. Or the inlet manifold mass flux rate, G₁.    -   3. Connecting channel geometries (heights, widths, lengths)    -   4. Connecting channel conditions (temperature, mole fractions,        adding/losing fluids)    -   5. Manifold geometries    -   6. Manifold conditions (temperature)        With the above information and the three-channel (N=3) system in        FIG. 1A, there are seventeen (6N−1) unknowns for a header        system:    -   Six (2N) header pressures (P_(1,A), P_(1,B), P_(2,A), P_(2,B),        P_(3,A), P_(3,B))    -   Three (N) connecting channel inlet pressures (P_(1,c), P_(1,c),        P_(1,c),    -   Three (N) header M2M manifold mass flux rates at the connection        inlet (G_(1,A), G_(2,A), G_(3,A))    -   Two (N−1) header M2M manifold mass flux rates at the connection        outlet (G_(1,B), G_(2,B))    -   Three (N) connecting channel mass flux rates (G_(c,1), G_(c,2),        G_(c,3))        The exact position of the pressures A and B for the manifold are        defined as follows: For the header, Position A at the manifold        connection i is defined as the intersection of the manifold        channel axis and the plane made by the manifold connection is        wall closest to the header manifold inlet. The header Position B        at the manifold interface i is defined as the intersection of        the manifold channel axis and the plane made by the manifold        connection is wall farthest from the header manifold inlet.        For the footer, Position A at the manifold connection i is        defined as the intersection of the manifold channel axis and the        plane made by the manifold connection i's wall farthest from the        footer manifold outlet. For the footer, Position B at the        manifold connection i is defined as the intersection of the        manifold channel axis and the plane made by the manifold        connection i's wall closest to the footer manifold outlet. The        plane “made” by the manifolds connection wall is a plane,        perpendicular to the central axis of the manifold, that        intersects an edge of the manifold connection.        The last mass flux rate in the M2M manifold header is zero,        because the manifold ends.

G _(3,B)=0  (13)

The 6N−1 unknowns are linked by the following 6N−1 equations:

-   -   Momentum balance for connecting channel i (N total), from        equation (9)    -   Momentum balance between connecting channel i and the manifold        (N total), also known as the “turning loss”, the resistance to        flow between the manifold and the manifold interface (can be a        gate or a grate):

$\begin{matrix}{{\left\lbrack \frac{P_{i,A} + P_{i,B}}{2} \right\rbrack - P_{i,C}} = {{\zeta \left( {\frac{G_{cc}A_{c,i}}{G_{i,A}A_{M,A,i}},\frac{A_{c,i}}{A_{M,A,i}}} \right)}\frac{G_{i,A}^{2}}{2\; \rho_{{Mc},i}}}} & (14)\end{matrix}$

-   -   where    -   A_(c,i) [m²]=Cross-sectional area of the connecting channel i,        at the manifold interface (not necessarily the area of the        connecting channel)    -   A_(M,A,i) [m²]=Cross-sectional area of the manifold at        connecting channel i    -   ζ [dimensionless]=Turning loss function from the M2M manifold to        the connecting channel    -   ρ_(M,c,i) [kg/m³]=Average density of the fluid between the        manifold and connecting channel i        The turning losses can be considered as part of a connecting        channel's total pressure drop and can have a strong effect on        flow distribution. The values of the turning loss are positive        for the header, and can possibly be positive or negative for the        footer, resulting in a pressure drop for the former and a net        static pressure increase for the latter. If the manifold        geometry and manifold connection geometry affect upon the        turning loss is well understood, such as large pipes, you can        use a correlation for the turning loss as those described in        Fried and Idelchik [“Flow resistance: A design guide for        engineers,” Hemisphere Publishing Corporation, 1989]. If that        isn't an option, another means of obtaining the turning loss        coefficient ζ for specific manifold geometry is obtaining from        experiment the pressures, upstream mass flux rate, the average        density and solving for ζ using equation 14. The header manifold        pressure at the interface can be used instead of the average of        P_(i,A) and P_(i,B) in equation (14), as it represents the        average pressure in the manifold across the manifold connection        interface.    -   Mass continuity equation between connecting channel i and the        manifold (N total)

A _(M,A,i) G _(i,A) −A _(M,B,i) G _(i,B) =A _(cc) G _(c,i)  (15)

-   -   where    -   A_(M,B,i) [m²]=Cross-sectional area of the manifold at        connecting channel i, downstream of the connecting channel    -   Mass continuity in the manifold between connecting channels i        and i+1 (N−1 total)

A _(M,A,i+1) G _(i+1,A) =A _(M,B,i) G _(i,B)  (16)

-   -   Manifold momentum balance at the connecting channel i, which        includes friction losses and momentum compensation terms (N        total)

$\begin{matrix}{{P_{i,A} - P_{i,B}} = {{{{k_{M}\left( {\frac{A_{m,B,i}G_{i,B}}{A_{M,A,i}G_{i,A}},{{Re}\left( \frac{G_{i,A} + G_{i,B}}{2} \right)}} \right)}\left\lbrack {G_{i,B}^{2} - G_{i,A}^{2}} \right\rbrack}\frac{1}{\rho_{M,i}}} + {4\; {f\left( {{Re}\left( \frac{G_{i,A} + G_{i,B}}{2} \right)} \right)}{\frac{L_{i,c}}{D_{i}}\left\lbrack \frac{G_{i,A} + G_{i,B}}{2} \right\rbrack}^{2}\frac{1}{2\; \rho_{M,i}}}}} & (17)\end{matrix}$

-   -   where    -   D_(i) [m]=Hydraulic diameter of the manifold at connection i    -   f [dimensionless]=Fanning friction factor for the manifold    -   k_(M) [dimensionless]=Momentum compensation factor    -   L_(i,c) [m]=Length of the connecting channel opening in the        manifold at connection channel i    -   ρ_(M,i) [kg/m³]=Average density of the fluid in the manifold at        connection channel i        The momentum compensation coefficient k_(M) always has a        positive value in the header, which can lead to leading to an        increase in static pressure across the manifold connection if        that effect is stronger than friction losses. Average mass flux        rates based on the upstream and downstream values are used for        this analysis. The effect of momentum compensation can vary the        pressure profiles in the header and footer greatly. If the        manifold geometry and manifold connection geometry affect upon        the momentum compensation coefficient k_(M) is well understood,        such as large pipes, you can use correlation for the turning        loss as those described in Pigford et al (“Flow distribution in        piping manifolds”, INDUSTRIAL & ENGINEERING CHEMISTRY        RESEARCH, v. 22, INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH,        pp. 463-471, 1983). If that isn't an option, another means of        obtaining the momentum compensation coefficient k_(M) for        specific manifold geometry is obtaining from experiment the        pressures, upstream and downstream mass flux rates, the average        manifold density and solving for k_(M) using equation (17).    -   Manifold momentum balance upstream of connecting channel i (N        total)

$\begin{matrix}{{P_{i,B} - P_{{i + 1},A}} = {\frac{4\; {f\left( {{Re}\left( \frac{G_{i,A} + G_{{i - 1},B}}{2} \right)} \right)}L_{u,i}}{D_{u,i}}\frac{\left( \frac{G_{i,A} + G_{{i - 1},B}}{2} \right)^{2}}{2\; \rho_{u,i}}}} & (18)\end{matrix}$

-   -   where    -   D_(u,i) [m]=Average hydraulic diameter of the manifolds upstream        section prior to connection channel i    -   L_(i,c) [m]=Length of the connecting channel opening in the        manifold at connection channel i    -   ρ_(u,i) [kg/m³]=Average density of the fluid in the manifold        upstream connection channel i        Thus, there are 6N−1 equations for 6N−1 unknowns. These        nonlinear equations can be solved simultaneously using a number        of solution strategies. If the manifold channel width is        constant in the manifold, the equations simplify. Note that, for        gases, the local average density is a function of local        pressure.

A similar set of 6N−1 equations can be written for the footer manifold.The direction of manifold flow is from A to B. The footer G_(1,A) valueis zero, as it is there is no flow prior to the first manifoldconnection. The manifold connection to manifold pressure drop inequation (14) would change the sign of the equation (14)'s right handside, along with the head term's mass flux basis to G_(i,B). The valueof the footer turning loss coefficient in (14) would be dependent uponG_(i,B), also. The footer manifold pressure at the interface can be usedinstead of the average of P_(i,A) and P_(i,B) in the footer version ofequation (14), as it represents the average pressure in the manifoldacross the manifold connection interface. The sign on the right handside of equation (15)'s continuity equation would change to negativewhile the continuity equation in (16) would be the same. Equation (17)'sform is the same, leading to a net decrease in static pressure from A toB caused by the combined friction and momentum compensation losses. Theonly change to equation (17) is that the ratio

$\frac{A_{M,B,i}G_{i,B}}{A_{M,A,i}G_{i,A}}$

is inverted so the footer manifold mass flow rate ratio is correct forthe footer. Equation (18) stays as is for the footer.

For footer Z-manifolds and footer L-manifolds the number order ofmanifold connection i increases follows in the same direction as theheader. The direction of G can be in the opposite direction of theheader for U-manifolds. This means the manifold interface numberingscheme goes in the opposite direction of the header.

M2M Manifold Physics

The flow of fluid takes the path of least resistance to leave amanifold. If the connecting channels have large pressure drop at thedesign flow rate compared to the manifold physics described in the lastsection, the flow distribution in the connecting channels will be mostlyequivalent and sophisticated manifold designs become less necessary. Ifthe connecting channels pressure drop at the design flow rate is lowcompared to the manifold pressure drops, then depending on the manifoldheader and footer pressure profiles there is potential for poor flowdistribution. The manifold physics versus the connecting channelpressure drop must be balanced to obtain the necessary connectingchannel flow distribution for a given manifold.

For low relative flow rates, friction losses dominate the staticpressure profiles in the manifolds because the small head values don'tgive rise to large turning losses or momentum compensation staticpressure changes. Examples of such cases include lab-on-a-chipanalytical devices and reactions with relatively long contact times. Todistribute flow to microsecond contact time reactors and fast liquidphase reactions, a manifold can potentially see very high mass fluxrates or velocities, even at low Reynolds numbers. These large headvalues can give rise to not only large friction losses but alsosubstantial turning and momentum compensation static pressure changes.The latter two pressure changes can strongly affect flow distribution inmanifolds.

Momentum compensation refers to the change in manifold static pressurebased on flow leaving and entering a manifold from a connecting channel.Momentum compensation increases the header static pressure each timefluid leaves the header to join the connecting channel, and it ispossible that the static pressure rise associated with momentumcompensation can be larger than friction losses at the connection. Therise in static pressure can be thought of as the means or “pushing” thefluid into the connecting channel. Momentum compensation acts todecrease static pressure in the footer, with the loss in static pressureattributed to accelerating the connecting channels flow in the directionof the manifold flow. The combination of momentum compensation andfriction losses can greatly decrease the footer static pressure in thedirection of M2M footer manifold flow.

Momentum compensation is a function of the mass flow rate ratio, theratio of the manifold flow rates just downstream to just upstream of adistribution point, and the flow regime of the fluid in the manifold.The mass flow rate ratio ranges from zero to one, and the mass flow rateratio is the ratio of the downstream to upstream mass flow rates for theheader and the ratio of the upstream to downstream flow rates for thefooter. Microchannel M2M manifolds with high enough heads can seemomentum compensation static pressure increases large enough to increasethe static pressure in the header despite frictional static pressurelosses, resulting in an increase of the static pressure driving forcefor flow to the connecting channels in the direction of flow. An exampleof the static pressure increase is seen in FIG. 2A, where the staticpressures in a header or footer calculated for a large M2M Z-manifoldsystem based upon turbulent pipe turning loss and momentum compensationcoefficients. Channel 1 is the first connecting channel that the headermanifold interacts with, while channel 19 is the last connecting channelthe footer interacts with. The momentum compensation effect in theheader drives the static pressure up with increasing channel number(direction of flow), despite frictional losses, while the combinedfrictional and momentum compensation losses in the footer drive thestatic pressure down with increasing channel number. The resultingpressure profile drives more flow to the higher number channels due tothe larger pressure differential driving force with the same connectingchannel flow resistance.

Experimental data for the microchannel header momentum compensationcoefficients versus local average Reynolds numbers are plotted in FIG.2B. The solid shapes show different manifold mass flow rate ratios(downstream over upstream). The header manifold mass flow rate ratio ofzero represents the last channel in the header, while one halfrepresents the second to last channel, assuming equal mass flow in bothconnecting channels. The value of the ratio increases as the channelsincrease in number from the end of the header manifold, up to a valueapproaching unity. As can be seen, the turning losses show a dependenceupon Reynolds number, as the headers see values in the laminar (Re<2200)to transition (2200<Re<4000-5000). For many curves a change in the M2Mheader momentum compensation coefficient can be seen at the transitionfrom laminar to transition flow. The M2M header momentum compensationcoefficient values tend to be on the same order or higher than seen inpipes from Pigford et al (“Flow distribution in piping manifolds”,INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH, v. 22, INDUSTRIAL &ENGINEERING CHEMISTRY RESEARCH, pp. 463-471, 1983) (values of 0.4-0.7).These M2M header momentum compensation values have experimentally leadto increases in header static pressure, even at inlet Reynolds numbersbelow 1000.

The average header Reynolds number is used as a basis of the M2Mmomentum compensation coefficient because this coefficient is obtainedfrom the experimental change in the static pressure from the beginningof the connecting channel to the exit by subtracting the frictionalpressure drop from it, which is based upon the average Reynolds numbers.As the connecting channel openings can be quite long in the direction offlow in the M2M manifold and spaced close together, the pressure canchange appreciably in the manifold, as mentioned in the previoussection.

The Reynolds number in the header can change appreciably in an M2Mmanifold due to its small hydraulic diameter and large mass flux ratesneeded to supply fast reactions, high effectiveness heat exchangers andother unit operations aided by microchannel architecture. Some preferredembodiments have operational contact times (contact times through theconnecting channels) of fifty milliseconds and less, and some havecontact times of ten milliseconds and less. The value of the Reynoldsnumbers in preferred embodiments can vary across the M2M manifold fromturbulent flow, to transition flow to laminar flow; in other preferredembodiments it can vary from transition flow to laminar flow. In otherpreferred embodiments it can vary from transition flow to turbulentflow. For M2M manifolds where the flow regime changes, the frictionlosses and the M2M momentum compensation losses, the latter seen in FIG.2B, change with it. These flow regime changes affect the pressureprofiles in the M2M manifold and can contribute to poor flowdistribution.

The turning loss is defined as the static pressure change the connectingchannel pays to divert the flow to and from the manifold to theconnecting channel. The turning loss is a function of

-   -   1. The cross-sectional area ratio of the connecting channel        interface over that of the manifold;    -   2. The local ratio of the mass flow rate of the connecting        channel to that of the highest manifold mass flow rate at the        connection, upstream or downstream; and    -   3. The shape of the manifold cross section. For rectangular        cross sections, the shape is quantified with the manifold aspect        ratio.

For constant values of the cross-sectional area of both the manifold andthe connecting channel interface, the header turning loss tends to behigher for the connecting channels closest to the header entrance thanto those farther downstream. This change in the turning loss withposition in the manifold is based upon the change in the manifold head:The head value decreases in the direction of header flow, so diverting afraction becomes less energy intensive.

FIG. 2C shows the experimental values of the M2M header manifold turningloss coefficient measured in a microchannel M2M header manifold with angrate interface to manifold area ratio of 0.09, plotted versus theconnecting channel to upstream M2M header manifold mass flow rate ratioof the grate interface to the manifold just upstream of the grateinterface. Also in FIG. 2C are the turning loss coefficients for largedimension manifold from Fried and Idelchik (“Flow resistance: A designguide for engineers,” Hemisphere Publishing Corporation, 1989) shown insolid line. In general, microchannel M2M (macro to micro) turning losscoefficients follow a similar trend to that of the Fried and Idelchikturning loss coefficients: the values increase with decreasingconnection to manifold cross-sectional area ratio. This implies that alarger pressure drop is needed to turn manifold flow into a smallerconnecting channel opening. The turning loss coefficient increases withincreasing connecting channel to upstream M2M header manifold mass flowrate ratio (or increase with position down the manifold, 0 being for thefirst channel, 1 for the last channel). However, the turning losses,based upon the product of the manifold head upstream of the grateinterface and the turning loss coefficient, are higher for the firstchannel in the header than for the last channel if the connection tomanifold cross-sectional area ratios are constant. This is because theincrease in the turning loss coefficients value with connecting channelto upstream M2M header manifold mass flow rate ratio approaching one(i.e. the end of the header) isn't as large as the decrease in themanifold head (G²/2/p) as the manifold loses mass flow rate

The microchannel turning losses in FIG. 2C are a factor of 2 to 5 higherthan turbulent pipe values, making the turning losses even higher thanpipes for connecting channel to upstream M2M header manifold mass flowrate ratios greater than 0.2. The manifold aspect ratio (largest side ofthe rectangle over the smallest) of the M2M manifold causes the highheader turning losses. M2M manifold channel heights are constrained bystacking limitations, as there is often a limited amount of heightavailable between repeating layers. Faced with the restriction ofchannel height, the M2M manifold can increase its width to increase theoverall manifold cross-sectional area for flow. By increasing themanifold cross-sectional area for flow, one can lower both frictionallosses and momentum compensation static pressure changes. By increasingthe cross-sectional area, the local manifold head is also decreased. Asthe M2M manifold channel aspect ratio increases, the flow turning fromthe manifold into the connecting channel sees increasing shear stressfrom the channel walls above and below. These wall shear stressesincrease the turning loss pressure drop with increasing M2M manifoldaspect ratio, where circular pipes and nearly square cross-sectionedducts have much less of this. For example, the M2M manifold channelaspect ratio for the M2M turning loss coefficient in FIG. 2C is roughly16:1.

For the footer turning losses, there is further interesting phenomena.FIG. 2D shows the negative values of the experimental M2M footer turningloss coefficients for the footer manifold plotted versus the localconnecting channel connecting channel to upstream M2M header manifoldmass flow rate ratio of the connecting channel to that of the highestmanifold flow rate at the connection, downstream of the footerconnection. The M2M footer turning loss coefficients in FIG. 2D are fora connecting channel interface to manifold area ratio of 0.09 and an M2Mmanifold aspect ratio of 16:1, and the large manifold numbers from Friedand Idelchik (“Flow resistance: A design guide for engineers,”Hemisphere Publishing Corporation, 1989) for the same connection tomanifold cross-sectional area ratio are plotted. The negative valuefooter turning coefficients for the pipe manifolds (from Fried andIdelchik) show a monotonic increase in the footer turning losscoefficient with increasing connecting channel to upstream M2M headermanifold mass flow rate ratio. These negative footer turning losscoefficients in FIG. 2D for both cases means that these coefficientshave a negative value, so when the footer turning loss coefficient ismultiplied by the manifold head downstream of the connecting channelthere will be a net increase in the static pressure from the connectingchannel outlet to the manifold. This static pressure increasecompensates for the static pressure header turning loss to some degree.The footer turning loss coefficient for the 16:1 M2M manifold aspectratio is a factor of two or three smaller than that of the Fried andIdelchik footer turning loss coefficients. The M2M manifold aspect ratiois probably a strong contributor to the difference in footer turningloss coefficient values, with wall shear stress lowering the net staticpressure increase compared to the large manifold system in Fried andIdelchik.

In summary, the experimental M2M manifold momentum compensation and M2Mmanifold turning losses coefficients diverge strongly in value fromreported values used for large pipe and duct systems, mostly due to theeffect of large M2M manifold aspect ratio manifold channels. These largeM2M manifold aspect ratios are needed to slow down the velocities in theM2M manifold, which in turn decrease local head values which drive thefriction, turning and momentum effects. To avoid making larger M2Mmanifold aspect ratios than the values described above and theirassociated turning losses, a wide M2M channel can be split into severalsmaller manifolds of smaller widths that distribute flow to a fractionof the total connecting microchannels. These smaller manifolds arereferred to as sub-manifolds. If the coefficients of momentumcompensation and turning losses are well understood for a given M2Mmanifold aspect ratio in a M2M manifold, it is possible to manipulatethe manifold and connecting channel cross-sectional areas to tailor theturning losses to compensate for other manifold static pressure changesfrom friction losses and momentum compensation static pressure changes.By tailoring the turning losses in a manner that will make the drivingforce for flow equal across the connecting channels despite the otherchanges in manifold pressure profiles, it is possible to reach anequivalent distribution of flow in each connecting channels. From thisdesire for controlling turning losses came the invention of variablecross-section grates and gates. Sub-manifolds, grates and gates arediscussed in the next section, in addition to other novel means ofcontrolling flow distribution in M2M manifolds.

M2M Distribution Layers

Flow into the M2M of a microdevice is usually routed through a largepipe, tube, or duct. Each large pipe or duct may further serve toconnect multiple microdevices operating in parallel. Flow distributionoccurs through multiple layers. One large pipe or duct meters flow toone or two or more microdevices. Once flow enters the microdevice, itmay then be further segregated into submanifolds. Each submanifoldserves to distribute flow to at least two or more connecting channels.Flow may then be further divided within a connecting channel intosubchannels.

Subchannels may be formed, for example, by the use of fins (eitherinserted before or after bonding) or integral (such as those formed fromthe laminae or shims). Flow in one microchannel may be divided into atleast two subchannels and in some embodiments, 10 to 100 subchannels.

Improved Distribution in Micro-to-Macro Manifolds

As discussed in the previous section, when the cross-sectional arearatio of the connecting channel to the manifold becomes small and theM2M manifold aspect ratio is high, the effect of turning pressure lossesin manifolds can be dramatic for the first channel in a header manifoldor the last channel in a footer manifold. If an M2M manifold distributesflow to a large number of connecting microchannels, the manifold widthcould be increased to slow the mass flux rate enough to avoid largeturning losses. This in turn decreases the connection to manifoldcross-sectional area ratio and increases the M2M manifold aspect ratioresulting in increasing turning losses. The turning losses add to theoverall connecting channel pressure drop (which includes frictional andother losses) and can lead to poor flow distribution. This is seen inmicrochannel process technology (MPT) devices in which large flows aredistributed across long distances to individual microchannels.

Splitting a larger M2M manifold into cascaded layers of smaller parallelM2M manifolds, each of which feed two or more connecting microchannelsor one large M2M manifold aspect ratio connecting microchannel canimprove flow distribution. A manifold can be split into separatemanifolds with walls, with each sub-manifold handling a fraction of thetotal flow. This change increases the connection to manifoldcross-sectional area ratio and lowers the cross-section's M2M manifoldaspect ratio, making turning losses lower. FIG. 3A shows a M2MZ-manifold split into two separate M2M sub-manifolds 312, 314. Thesub-manifold includes length in addition to the distribution zone oflength L_(M2M). This additional length can be used to tailor thepressure drop for the sub-manifold.

The width of the sub-manifold section between a macro manifold and aconnecting channel distribution section can be changed to affect thesub-manifolds flow resistance. FIG. 3B shows a sub-manifold design foran L-manifold with two sub-manifolds and connecting channels ofequivalent flow resistance. The width of the sub-manifold with thelonger upstream flow path, w₂, is wider than the path for thesub-manifold with the shorter upstream flow path, w₁. This difference inupstream widths allows a means of decreasing the flow resistance for thelonger flow path sub-manifold and increasing the flow resistance of theshorter flow path sub-manifold so that both sub-manifolds can meter thesame amount of total flow. A similar method to this L-manifoldssub-manifold width design can be used for U-manifolds, which have asimilar problem matching pressure drops in multiple sub-manifolds withthe added burden of matching the total flow resistance betweensub-manifold that include headers and footers of differing lengths. Anadditional benefit can be that the walls separating sub-manifolds canact as pillars of mechanical support to handle loads applied the wallshims directly above and below in the direction of stacking.

Channel walls often need some material to hold the ends together in away that avoids creating long and dangling features that could shiftposition during fabrication and/or operation. FIG. 3C shows an examplein which one or more shims whose microchannels end in a bar 37perpendicular to the channels' axes, signaling the end of themicrochannel. In this example, the bar 37 forms a grate that defines oneside of a manifold 370. The plane created by the bar 37 and the openspace in the adjacent channel is the connecting channel plane exit orentrance. This connecting channel plane design is similar to thatillustrated by Golbig et al and discussed in Example 1, except theconnecting channel in Golbigs stays in the plane under 37 and doesn'textend into the plane of 37.

An example is shown in FIG. 3D. In this example, each crossbar 39 (uppershim), 38 (lower shim) forms a portion of the grate. The opening 36created by the differences in the shim channel's ends creates aninterface for fluid flow between the microchannels 35 and the M2Mmanifold.

In some embodiments, it is better to have more of the M2M zone availablefor flow to lower the M2M mass flux rates, which in turn could lower themomentum compensation static pressure changes, turning and frictionlosses. FIG. 3D shows the “grate” concept for a single sub-manifold. Forthe header 384, fluids flows in the M2M and turns into and over theoutstretched “grate” 38, entering the interface channel 36 created bythe lower shim 38 and the upper shim 39 that marks the end of themicrochannel. The flow then leaves the interface and enters themicrochannels 35. The flow distribution can be tailored by varying thedegree the “grate” sticks out into the manifold over the length of a M2Mmanifold and also by varying the width of the opening 36 under thecrossbar 33. The design in FIG. 3D has been tested in a flowdistribution test device.

A “gate” connects an M2M manifold to two or more connectingmicrochannels. Gate features can help distribute flow with a lowerpressure drop than a conventional orifice, which seeks to obtain flowdistribution by making all the flows pay an equally large suddenexpansion and contraction pressure drop. The gate uses turning losses tometer flow to a connecting channel, set of connecting channels, orsubmanifold, and does so by varying the gate cross-sectional area. Thistailoring of the turning loss allows the gate to compensate for changesin the manifold pressure profiles so that the connecting channelpressure drops are equivalent. Gates also use friction losses, expansionand other distribution features to add back pressure. By varying gatecross-sectional area it is possible to add back pressure to or removebackpressure from a sub-manifold in a larger manifold cascade as a meansof controlling overall sub-manifold flow resistance.

In L-manifolds, orifice gates 31 in the connecting channel smooth outdistribution by forcing flow through a narrowed opening in the entranceof the connecting channels. FIGS. 3E and 3F show an example of a gate,with an opening in the gray shim to let in flow through the wall createdby the stacking of two or more shims. This “gate” is an extension of the“grate” design in that it brings an end to the connecting microchannelsin shim geometry and allows access to the microchannels from the M2Mmanifold.

Gates and grates use the turning losses to equalize the static pressureprofiles at the connecting channel interfaces, but the manner in whichthey do so are different from orifices. Orifices use constant smallmanifold connection cross-sectional areas to impose large flowresistances for each connection, and incur large operating costs in theform of higher overall pressure drops. The inventions described in gatesand grates use two or more openings of varying cross-sectional area touse the naturally occurring turning losses to overcome the manifoldstatic pressure profiles caused by manifold physics. In Example 3, thegate openings in the direction of flow decrease in size to compensatefor the larger turning losses for the first opening and the increasedstatic pressure driving force at the last two gates caused by momentumcompensation. These gate sizes help control flow without the largepressure drops associated with orifice flow resistance. For gates andgrates, the preferred value of DPR₂ is greater than two, more preferablygreater than 5, in some preferred embodiments it is greater than 10, andin some embodiments 5 to 30. The higher the ratio, the less operationalcosts incurred by the manifold from pressure drop it gives.

Decreasing the cross-sectional area of the gates in the direction offlow (see FIG. 3G) in a header manifold improves distribution because(1) a large gate width at the first openings compensates for the largerrelative turning losses seen for the first interface in the manifold;and (2) for gates downstream of the first gate, decreasing the gate sizeand increasing the turning loss penalty can counteract the increase instatic pressure down the length of the manifold, caused by manifoldmomentum compensation.

Flow Regime

The relative momentum of the manifold stream flow plays an importantpart in manifold physics. For M2M manifolds with large head values,momentum compensation and turning losses become more pronounced, and canhave greater influence on fluid flow distribution than manifold frictionlosses. However, if the manifold flow does not have a large head value,the friction losses become the dominant effect and the use of manifoldfeatures that compensate for the high momentum phenomena lose theireffectiveness. As mentioned previously, microchannel M2M manifolds canachieve large head values at low Reynolds numbers because their smallhydraulic diameters compensate for large velocities and mass flux rates.These large head values can occur in laminar flow regimes, well belowthe Reynolds number values of transition and turbulent flow. With largepipe and duct manifolds systems the same head values would be in theturbulent regime due to their inherently larger hydraulic diameters.

The regime of flow entering a macromanifold is typically turbulent ortransition. The flow then undergoes additional regime change in themanifold within the microdevice from turbulent, to transition, tolaminar. Alternatively, the flow may only undergo one regime change,from turbulent to transition or from transition to laminar.

As a means of determining if a M2M manifold has a large head value, wecan use the ratio Mo:

$\begin{matrix}{{Mo} = {\frac{\frac{1}{2\; \rho}\left\lbrack {G^{2} - 0} \right\rbrack}{\frac{4\; {fL}_{M\; 2\; M}}{D}\frac{G^{2}}{2\; \rho}} = \left\{ \frac{4\; {fL}_{M\; 2\; M}}{D} \right\}^{- 1}}} & (19)\end{matrix}$

whereD [m]=manifold hydraulic diameter at the M2Mf [dimensionless]=Fanning friction factor for the M2M. The source ofFanning friction factors for channels is given in Rohsenow et al[“Handbook of Heat Transfer”, 3^(rd) ed. McGraw Hill, 1998] for a widerange of channel geometries, along with references. Care should beplaced in using appropriate Reynolds numbers, channel geometry factors(such as aspect ratios), and hydrodynamic dimensionless lengths(x⁺=L_(M2M)/D/Re for laminar flows) for the Fanning friction factor.G [kg/m²/s]=mass flux rate at the M2MRe [dimensionless]=Reynolds number at the M2MThe ratio Mo (see equation 18) compares the largest M2M manifold headvalue, the driving force for turning losses and momentum compensationstatic pressure changes, to the friction losses the manifold would seeif the largest M2M manifold head was applied over the entire manifoldlength L_(M2M). Small values of Mo would indicate that the M2M effectswould be small in comparison to the friction losses, negating some ofthe effectiveness of sub-manifolds and all the effectiveness of gratesand gates to control flow distribution. If the Mo value was greater thansome small ratio, for example, Mo>0.05, the head driven turning lossesand momentum compensation terms contribute to flow distribution. Forcases when Mo is greater than 0.05 sub-manifolds, grates, gates andother architecture that manipulate the turning losses and manifoldstatic pressure profiles can improve M2M manifold flow distribution. Forcases when Mo is less than 0.05, manifold friction losses dominate flowdistribution.

An alternate for the Mo number is the FA number. The purpose of FAnumber is to avoid the laminar creeping flow distributed over shortmanifold lengths. The FA expression is a function of flow rate/flowregime (or Reynolds number), hydraulic diameter of manifold and Lengthof manifold. Below is the expression of FA number:

${FA} = {\frac{\left\lbrack {0.058 + {0.0023\left( {{In}\mspace{14mu} {Re}} \right)^{2}}} \right\rbrack^{2}}{L_{M\; 2\; M}} < 0.01}$

where hydraulic diameter D in inches, manifold length L_(M2M) in inchesand Reynolds number Re have the same definition as that for Mo.

In preferred embodiments, FA<0.01. For example, if the hydraulicdiameter of sub-manifold is 0.080″ (0.20 cm), then the table below givesthe length requirement of a sub-manifold with FA<0.01.

Reynolds Length of sub- number manifold (in) 10 L_(M2M) > 0.04″ 100L_(M2M) > 0.09″ 1000 L_(M2M) > 0.23″ 10000 L_(M2M) > 0.51″ 100000L_(M2M) > 1.05″This means for Re=10 and D=0.08″ (0.20 cm), any manifold design withsub-manifold length >0.04″ (0.10 cm) will have FA<0.01.

Construction of a 5 Stream, Integrated Combustor and Reformer

A microchannel-based module was designed to perform steam-reforming ofmethane, with heat supplied by combustion of air and fuel. Thecombustion and steam reforming reactions are conducted in the samedevice, which has three zones:

Manifold: The manifold zone distributes flow into the channels. Thereare five streams that need to be manifolded. These streams are—Fuel,Air, Exhaust, Reactant and Product. Fuel and air comes into the deviceand leaves out as exhaust. The reactant comes in, gets processed andexits as Products.

Heat exchanger: The exhaust and the products leaving the device are athigh temperature. The heat exchanger recuperates the heat from exhaustand product streams to fuel, air and reactant streams. This recuperationhelps in achieving the necessary temperature of streams for chemicalreactions in the reactor.

Reactor: The reactor zone is actually a reactor plus a heat exchanger.Most of the chemical reactions occur in the reactor zone. The reactionsoccurring in the device are: combustion in the fuel channel (bothcatalytic and homogeneous), and catalytic steam methane reformingreaction in reactant channel. In an optional embodiment, somepre-reforming of either the fuel or process feed may occur in acatalytically coated heat exchanger section.

The fuel channel is coated with different types of catalyst whichpromotes combustion at low temperatures (heterogeneous combustion). Theheat of combustion is transferred through the wall to the reactionchannel. This heat drives the steam-reforming reaction.

A module combustion M2M manifold was designed to achieve equal flowdistribution of combustion reaction streams (fuel such as natural gas,hydrogen, carbon monoxide, and the like with or without air to the fuelside, air to the air side) to the array of combustion channels so thatthey would mix inside the connecting microchannels within the module.The air and fuel enter from opposite sides of the module, mix within thecombustion section, and the combined exhaust makes a u-turn beforetraveling down the return microchannel and leaves the end of the module,forming header L-manifolds for both streams.

Since each M2M manifold feeds multiple separate millisecond contact timemicrochannel reactors (72 in this example, but could range from severalto tens of hundreds), it has to distribute large flow rates that havehigh dynamic pressure (G²/(2ρ)=ρU²/2) values. The total combined M2M andchannel pressure drop was important, and achieving a good distributionof air and fuel in each channel was especially important due to the needto mix near stoichiometric mixtures of fuel and oxidant (air). The meansof achieving equal flow distribution for this system was complicated bya number of fabrication and macro manifold constraints. The resultingdesign included innovations such as: multiple (six, in the illustratedexample) sub-manifolds with multiple (12) channels per sub-manifold; andmultiple (3) gates per sub-manifold with multiple (4) downstreamconnecting channels per gate.

FIG. 4A is an exploded view of shims in the stacked device. FIGS. 4-22are overhead views of shims that were assembled into the device. Theoverall size of all the shims is 31.47″ (length)×22.00″ (width). Theshim length and width are as defined in FIG. 4B. The thickness of theshim is defined in the direction perpendicular to length and width.Shims from 1-28 were stacked on top of each other to form a repeatingunit of the device. The stack height of the repeating unit is 0.43″.There are total 49 repeating units in the device. The overall height ofthe device is 23.1″. For all the shims, a perimeter margin of 1.00″along the length and 1.50″ along the width has been marked. This markedperimeter metal does not become the part of final device and wasprovided only to enhance metal diffusion bonding. Toward the bottom andsides of all the shims, rectangular slots are made. The purpose of theseslots is to provide a location indicator for opening sub-manifoldsduring post-bonding fabrication operations, such as plungeelectrodischarge machining. The slots on the right side are for fuelstream 12 and reactant stream 14 sub-manifolds, the slots on the leftside are for air stream 16 and product stream 18 and the slots at thebottom 19 are for exhaust stream.

All the openings in the shims are through slots or holes. Passages forthe flow in the device are through slots or holes. The flow between thepassages is separated either by ribs (within a shim for the same stream)or wall shims (between different streams)

FIG. 4B shows a wall shim. The thickness of the shim is 0.020″. Thisshim separates the reforming reaction stream from the fuel stream. Theshim also transfers heat generated in combustion channels to thereaction channels for the steam reforming reaction.

FIG. 5 shows a wall shim. The thickness of the shim is 0.020″. This shimseparates the reactant stream from fuel stream. The shim also transfersheat generated in combustion channels to the reactant channels for steamreforming reaction. The slots 32 in the shims are to hold catalystsupport fins in the fuel channel

FIG. 6 shows a shim that forms the passage for fuel stream. Thethickness of the shim is 0.012″. The slots on the shims form featuresfor the fuel stream. The fuel enters from the right end of the shimthrough 6 inlets 44 (referred as sub-manifolds). The widths of thesesub-manifolds perpendicular to the direction of flow, starting from thebottom are 0.60″, 0.60″, 0.55″, 0.50″, 0.50″ and 0.40″. All sixsub-manifolds are separated by 0.060″ rib. The lengths of thesub-manifolds in the flow direction, starting from the bottom are16.93″, 14.11″, 11.29″, 8.47″, 5.65″, and 2.83″. The flow from eachsub-manifold distributed into three super-channels as shown in thedrawing. The flow goes over a 0.060″ rib to enter the super-channel fromsub-manifolds. The length of super-channels in the direction of flow is0.50″. Each super-channel further divides the flow into four channels.the numerous thin channels 42 are separated by 0.060″ ribs except forevery 4th rib which is 0.120″. All the channels 42 are 0.160″ wide. Theflow passes through the heat exchanger zone 46, receiving heat fromexhaust and product stream and enters combustion zone 48. In thecombustion zone, fuel mixes with air and combusts in the presence ofcombustion catalyst.

FIG. 7 shows another shim that forms the passage for fuel stream inconjunction with the shim shown in FIG. 6. The thickness of this shim is0.025″. The slots on the shims form features for fuel stream. The fuelenters from the right end of the shim through 6 inlets 52 (referred assub-manifolds). The widths of these sub-manifolds perpendicular to thedirection of flow, starting from the bottom are 0.60″, 0.60″, 0.55″,0.50″, 0.50″ and 0.40″. All six sub-manifolds are separated by 0.060″ribs 54. The lengths of the sub-manifolds in the flow direction,starting from the bottom are 16.93″, 14.11″, 11.29″, 8.47″, 5.65″, and2.83″. The sub-manifolds have small openings 56 (gates) to meter theflow into the channels. Each sub-manifold has 3 gates. There are a totalof 18 gates to meter the flow into the channels. The length of the gatesin the flow direction is 0.060″. The widths of the gates starting fromthe right are—0.105″, 0.102″, 0.094″, 0.122″, 0.199″, 0.103″, 0.143″,0.142″, 0.127″, 0.160″, 0.161″, 0.145″, 0.299″, 0.230″, 0.152″, 0.560″,0.555″, and 0.550″. The channels 58 are separated by 0.060″ ribs exceptfor every 4th rib which is 0.120″. All the channels are 0.160″ wide. Theflow passes through the heat exchanger zone 57, receiving heat fromexhaust and product stream and enters combustion zone 59. In thecombustion zone, fuel mixes with air and combusts in the presence ofcombustion catalyst.

FIG. 8 illustrates a jet shim that acts as a wall shim between fuel andair stream in the manifold and heat exchanger zone. The thickness ofthis shim is 0.010″. In the combustion zone, this shim provides passages62 (referred as orifices) to mix air into fuel. For every channel (fuelor air), there are 18 orifices to mix air into fuel. Beginning from thebottom, the first orifice is rectangular slots with semi-circular endsof diameter 0.012″. The longest length of the slot is in the directionof flow. The second orifice is equilateral triangular in shape with0.012″ side length and is placed at a distance of 0.133″ from firstorifice. The third & fourth orifices are of 0.012″ diameter holes placed0.267″ from the first orifice. The fifth orifice is again a sametriangular slot placed 0.386″ from the first orifice. Orifice six tofifteen are circular holes with diameter 0.012″ and are placed at0.594″, 0.769″, 0.969″, 1.168″, 1.615″, 2.112″, 2.658″, 3.257″, 3.257″,3.857″, 4.624″ from the first orifice. Orifice sixteen and seventeen are0.012″ diameter holes place 5.392″ from first orifice.

A continuous 0.050″ slot 64 is made on the top of the shim to transportcombusted fuel (exhaust) over to exhaust channel. This slot allows flowto travel between connecting channels in between the header and thefooter.

FIG. 9 shows the shim that forms the passage for the air stream. Thethickness of the shim is 0.012″. The slots on the shims form featuresfor air stream. The air enters from the left end of the shim through 6inlets 92 (referred as sub-manifolds). The widths of these sub-manifoldsperpendicular to the direction of flow, starting from the bottom are0.60″, 0.60″, 0.55″, 0.50″, 0.50″ and 0.40″. All six sub-manifolds areseparated by a 0.060″ rib. The lengths of the sub-manifolds in the flowdirection, starting from the bottom are 16.93″, 14.11″, 11.29″, 8.47″,5.65″, and 2.83″. The flow from each sub-manifold distributes into threesuper-channels 94 as shown in the drawing. The flow goes over 0.060″ rib96 to enter the super-channel from sub-manifolds. The length ofsuper-channels in the direction of flow is 0.50″. Each super-channelfurther divides the flow into four channels. These channels areseparated by 0.060″ ribs except for every 4th rib which is 0.120″. Allthe channels 99 are 0.160″ wide. The flow passes through the heatexchanger zone, receiving heat from exhaust and product stream andenters the combustion zone. In the combustion zone, air flows into theF1 (FIG. 4) and F2 shim (FIG. 5) through orifices 62 to combust thefuel. A continuous 0.050″ tall slot 95 is made on the top of the shim totransport combusted fuel (exhaust) over to the exhaust channel

FIG. 10 shows another shim that forms the passage for the air stream inconjunction with the shim shown in FIG. 9. The thickness of the shim is0.025″. The slots on the shims form features for the air stream. The airenters from the left end of the shim through 6 inlets (referred assub-manifolds). The widths of these sub-manifolds perpendicular to thedirection of flow, starting from the bottom are 0.60″, 0.60″, 0.55″,0.50″, 0.50″ and 0.40″. All six sub-manifolds are separated by a 0.060″rib. The lengths of the sub-manifolds in the flow direction, startingfrom the bottom are 16.93″, 14.11″, 11.29″, 8.47″, 5.65″, and 2.83″. Thesub-manifolds have small openings (gates) to meter the flow into thechannels. Each sub-manifold has 3 gates 104. There are total 18 gates tometer the flow into the channels. The length of the gates in the flowdirection is 0.060″. The widths of the gates starting from the rightare—0.188″, 0.175″, 0.172″, 0.165″, 0.167″, 0.167″, 0.240″, 0.235″,0.232″, 0.260″, 0.260″, 0.260″, 0.277″, 0.277″, 0.277″, 0.590″, 0.580″,and 0.588″. The channels are separated by 0.060″ ribs except for every4th rib which is 0.120″. All the channels are 0.160″ wide. The flowpasses through the heat exchanger zone, receiving heat from exhaust andproduct stream and enters the combustion zone. In the combustion zone,air flows through the jet shim to react with the fuel in the fuelchannels. A continuous 0.050″ tall slot 106 on the top of the shim totransports combusted fuel (exhaust) over to exhaust channel

FIG. 11 shows a wall shim that separates the air stream from the exhauststream. The thickness of the shim is 0.010″. On the top of the shimthere are slots through which combusted fuel (exhaust) passes over tothe exhaust channel

FIG. 12 shows a shim with exhaust stream channels. The thickness of theshim is 0.020″. The exhaust stream flows from top of the shim to thebottom of the shim. All the passages for the flow are 0.160″ wide andare separated by 0.060″ ribs except for every 4th rib which is 0.0120″.The exhaust enters a passage from a U-turn at the top of the shim,passes through the heat exchanger zone exchanging heat with fuel and airand flows out at the bottom of the shim

FIG. 13 shows a shim with exhaust stream channels that pair with thechannels in the shim shown in FIG. 12. The thickness of the shim is0.020″. The exhaust stream flows from top of the shim to the bottom ofthe shim. All the passages for the flow are 0.160″ wide and areseparated by 0.060″ ribs except for every 4th rib which is 0.0120″. Theexhaust enters at the top of the shim in the reactor zone, passesthrough the heat exchanger zone exchanging heat with fuel and air andflow out at the bottom of the shim. At the bottom, a rib 132 of 0.060″serves as support for bonding.

Another shim identical to the shim in FIG. 12 is stacked over the shimin FIG. 13.

Another shim identical to the shim in FIG. 11 is next in the shim stack.Followed by another shim identical to that shown in FIG. 10. Followed byanother shim identical to that shown in FIG. 9. Followed by another shimidentical to that shown in FIG. 8. Followed by another shim identical tothat shown in FIG. 7. Followed by another shim identical to that shownin FIG. 6. Followed by another shim identical to that shown in FIG. 5.Followed by another shim identical to that shown in FIG. 4B.

FIG. 14 shows the shim that forms the passage for reactant stream. Thethickness of the shim is 0.010″. The slots in the shim form passages forthe flow of reactant stream. The reactant enters from the right end ofthe shim through 6 inlets 142 (referred as sub-manifolds). The widths ofthese sub-manifolds perpendicular to the direction of flow are 0.539″.All six sub-manifolds are separated by 0.060″ rib. The lengths of thesub-manifolds in the flow direction, starting from the bottom are16.93″, 14.11″, 11.29″, 8.47″, 5.65″, and 2.83″. The sub-manifolds havesmall openings 144 (gates) to meter the flow into the channels. Eachsub-manifold has 3 gates. There are a total 18 gates to meter the flowinto the channels. The length of the gates in the flow direction is0.060″. The widths of the gates starting from the right are—0.229″,0.209″, 0.173″, 0.229″, 0.209″, 0.173″, 0.229″, 0.209″, 0.173″, 0.229″,0.209″, 0.173″, 0.229″, 0.209″, 0.173″, 0.229″, 0.209″, and 0.173″. Thechannels are separated by 0.060″ ribs except for every 4th rib which is0.120″. All the channels are 0.160″ wide. The length of the flow passagein the shim from the respective sub-manifold is 0.70″. In the reactorzone, slots 146 (7.00″ long and 0.82″ wide) are made. The purpose ofthese slots is to hold the fins which provide surface area forsteam-reforming reaction.

FIG. 15 shows another shim that forms the passage for reactant stream inconjunction with the shim shown in FIG. 15. The thickness of the shim is0.012″. The reactant enters from the right end of the shim through 6inlets 152 (referred as sub-manifolds). The widths of thesesub-manifolds perpendicular to the direction of flow are 0.539″. All sixsub-manifolds are separated by 0.060″ rib. The lengths of thesub-manifolds in the flow direction, starting from the bottom are16.93″, 14.11″, 11.29″, 8.47″, 5.65″, and 2.83″. The flow from eachsub-manifold distributed into three super-channels as shown in thedrawing. The flow goes over a 0.060″ rib 154 to enter the super-channel156 from sub-manifolds. The length of super-channels in the direction offlow is 0.539″. Each super-channel further divides the flow into fourchannels 158. Channels are separated by 0.060″ ribs except for every 4thrib which is 0.120″. All the channels are 0.160″ wide. The flow passesthrough the heat exchanger zone, receiving heat from product and exhauststream and enters the reactor zone. In the reactor zone, the steamreforming reaction occurs in the presence of combustion heat.

FIG. 16 shows a wall shim that separates the reactant stream from theproduct stream. The thickness of the shim is 0.010″. A continuous 0.050″slot 162 is made on the top of the shim to transport products formed inthe reactant channel over to the product channel.

FIG. 17 shows the wall shim and separates the reactant stream from theproduct stream. The thickness of the shim is 0.010″. A continuous 0.21″tall slot 172 is made on the top of the shim serves to transportproducts formed in the reactant channel over to the product channel

FIG. 18 shows a shim for product flow. The thickness of the shim is0.018″. The product flows in the passages from the top of the shim tothe bottom of the shim. Passages are 0.160″ wide and are separated by0.060″ rib except for every 4^(th) rib which is 0.120″ wide. The flowfrom the passages is then collected in another set of passages 184(referred as sub-manifold) that run perpendicular to first set ofpassages. These passages are separated from first set of passages by0.060″ ribs that in conjunction with shims in FIG. 17 and FIG. 19form“grate. The width of each sub-manifold in the directionperpendicular to flow direction is 0.539″. The lengths of sub-manifoldsin the flow direction starting from bottom sub-manifold are 16.93”,14.11″, 11.29″, 8.47″, 5.65″, and 2.83″.

FIG. 19 shows a wall shim that separates reactant stream from productstream. The thickness of the shim is 0.010″. A continuous 0.21″ tallslot 192 is made on the top of the shim to transport products formed inthe reactant channel over to the product channel

FIG. 20 shows a wall shim and separates reactant stream from productstream. The thickness of the shim is 0.010″. A continuous 0.050″ tallslot 202 is made on the top of the shim to transport products formed inthe reactant channel over to the product channel.

FIG. 21 shows the shim that forms the passage for reactant stream. Thethickness of the shim is 0.012″. The reactant enters from the right endof the shim through 6 inlets 212 (referred as sub-manifolds). The widthsof these sub-manifolds perpendicular to the direction of flow are0.539″. All six sub-manifolds are separated by 0.060″ ribs 214. Thelengths of the sub-manifolds in the flow direction, starting from thebottom are 16.93″, 14.11″, 11.29″, 8.47″, 5.65″, and 2.83″. The flowfrom each sub-manifold distributed into three super-channels 216 asshown in the drawing. The flow goes over a 0.060″ rib 218 to enter thesuper-channel from sub-manifolds. The length of super-channels in thedirection of flow is 0.539″. Each super-channel further divides the flowinto four channels 219. Channels are separated by 0.060″ ribs except forevery 4th rib which is 0.120″. All the channels are 0.160″ wide. Theflow passes through the heat exchanger zone, receiving heat from productand exhaust stream and enters the reactor zone. In the reactor zone, thesteam reforming reaction occurs in the presence of combustion heat.

FIG. 22 shows a drawing of a shim that in conjunction with shim in FIG.21 forms the flow channels for reactant stream. The slots in the shimform passages for the flow of reactant stream. The reactant enters fromthe right end of the shim through 6 inlets (referred as sub-manifolds).The widths of these sub-manifolds perpendicular to the direction of floware 0.539″. All six sub-manifolds are separated by 0.060″ rib. Thelengths of the sub-manifolds in the flow direction, starting from thebottom are 16.93″, 14.117″, 11.29, 8.47″, 5.65″, and 2.83″. Thesub-manifolds have small openings (referred as orifices) to meter theflow into the channels. Each sub-manifold has 3 orifices. There aretotal 18 orifices to meter the flow into the channels. The length of theflow opening in the flow direction is 0.060″. The widths of the openingsstarting from the right are—0.229, 0.209″, 0.173″, 0.227″, 0.209″,0.173″, 0.229″, 0.207″, 0.173″, 0.227″, 0.209″, 0.173″, 0.227″, 0.209″,0.173″, 0.229″, 0.209″, and 0.173″. The channels are separated by 0.060″ribs except for every 4th rib which is 0.120″. All the channels are0.160″ wide. The length of the flow passage in the shim from therespective sub-manifold is 0.70″. In the reactor zone, slots (7.00″ longand 0.82″ wide) are made. The purpose of these slots is to hold the finswhich provide surface area for steam-reforming reaction.

Manifolding and Microchannel Features

Cross-sectional area restrictions in gates and grates, preferably at thefront of connecting channels, can be formed, for example, by: holesthrough walls, bumps from a lower surface, wall projections, andcombinations of these. Features such as rounded bumps can be formed byetching.

Manifold walls can be rounded (such as to appear like a race track).Flow into a manifold can enter from above or below; and, in manypreferred embodiments, in-plane, such as from a side header attached tothe side of a laminated shim stack. Manifold walls can be solid or withgaps.

In some embodiments (see FIG. 23), a manifold (in the illustrated case,a footer) can be used to separate two phases of differing density in amicrochannel device by gravity and/or centrifugal forces.

Walls between connecting channels may be the same or different lengths.Gates to groups of channels can be centered or offset from the center ofthe gate's connecting channels. FIG. 24 illustrates a manifold structurewith an offset gate and channels of differing lengths. In theillustrated manifold, flow momentum (of a stream entering from the sideof the connecting channels) for a centered gate would tend to force thegreatest flow through downstream channel 242 on the far right side dueto the incoming stream coming from left to right; however, the gate 244positioned in the downstream portion of the manifold (in the illustratedembodiment, the gate is attached to the downstream manifold wall 246)blocks a portion of the flow. Another feature that can be usedindependently of or in conjunction with offset gates are longer internalwalls 248 (not 246) positioned downstream (relative to the direction offlow into the manifold) to restrict flow. Thus, flow is more equallydistributed through the connecting channels. In preferred embodiments,at least one internal channel wall in the downstream section 249 of aconnecting channel set is longer than a channel wall in the upstreamsection. More preferably, at least two (or at least 4) internal channelwalls in the downstream section 249 of a connecting channel set arelonger than a channel wall in the upstream section. Still morepreferably, the downstream section 249 of a connecting channel setcontains at least two internal channel walls 243, 248 that projectprogressively further into a manifold zone 245. Preferably, there are acombination of an offset and at least one internal channel wall in thedownstream section 249 of a connecting channel set longer than a channelwall in the upstream section, since this combination can provide moreequal flow distribution (smaller Q₁ or Q₂) for large flow rates thaneither feature individually. In this embodiment, “longer” meansprojecting the channel further into a manifold zone 245. A similardesign concept can also be used for the footer. When the steams of twoor more connecting channel combine at a manifold connection, the streamfrom the connecting channel farthest from the footer manifold's outletwill have a larger momentum vector in the manifold's flow direction thanthose connecting channel closer to the manifold's exit. This will lowerthe flow resistance for the farthest away channel for leaving themanifold connection, so to balance the flow leaving the channels we canthen vary the geometry around the channel as described above for 242.

FIG. 25 a illustrates flow straightening in a multiple gateconfiguration. Flow enters from the side and is momentum biased towardflow through the downstream portion of the connecting channels. Gates256, 258 can be used to equalize flow between channel sets 257, 259.Flow through connecting channels 254 can be equalized by extending thelength of a manifold zone a distance L₂ (or, in the case of FIG. 25 a, asubmanifold zone 252). Preferably, the zone has a length L₂ of at leastthree times longer than the manifold length L_(M2M) (see FIG. 1A) in theflow direction, in some embodiments at least 6 times longer than themanifold length L_(M2M), in some embodiments, to save space L₂ is 20times or less longer than the manifold length L_(M2M). Unless correctedby other means, shorter zones suffer from biased flow while excessivelylong zones may unnecessarily add cost and reduce performance (forexample, by adding frictional losses). Like all features describedherein, this feature can be combined with the other designs describedherein.

FIG. 25 b shows a manifold with a straightening zone 2502 and a flowbump (a grate) 2504 before the entrance of the connecting channels 2506.Entering stream 2505 may come from a side manifold in which flowemanates from above, below, or in the plane. FIG. 25 c is an explodedview of sheets that can be used to form the manifold/channel structure.

FIGS. 26 a and 26 b illustrate a manifold 262 with straight connectingchannels 264. The connecting channels are partially blocked by flowbumps 266. The flow enters the connecting channels from the manifold,but can redistribute amongst channels through the cross-connectingchannels underneath the connecting channels. Two such cross-connectingchannels are shown in FIG. 25 a, made by the layer 266. The advantagefor such a system is that cross-connecting channels in 266 can allow forredistribution of flow should manifold design not allow for acceptabledistribution due to space constraints.

A modified version of the structure of FIG. 26 could be microchannelapparatus, comprising: an array of parallel microchannels disposed in aplane; wherein the array of parallel microchannels are connected at oneend by an inlet manifold and at their opposite end by an outletmanifold; and at least one channel disposed above or below the array ofparallel microchannels and disposed at an angle of at least 20 degrees(preferably substantially 90 degrees) relative to the parallelmicrochannels and disposed between the inlet manifold and outletmanifold and connected via openings to the parallel microchannels in thearray. Such a structure could be obtained by forming connections throughthe walls 265, 267 of second channel 261. The connections through thewalls 265, 267 would connect to an inlet and outlet respectively so thatthere could be cross flow through the second channel. In someembodiments (not shown) a plate can separate the first and second layersexcept for an aperture or apertures through the plate to providecommunication between the first layer and the second channel. Such aconstruction could be used, for example, to mix components or as apathway to add a coating material from one layer to the next.

FIG. 27 is an exploded view (also a preassembled view) of an alternativedesign having flow bumps 272, 274 in an alternating arrangement suchthat there is no straight flow path through the connecting channels.This structure creates extensive interchannel mixing.

In addition to flow distribution, manifolds may also perform a mixingfunction. FIG. 28 illustrates a manifold with cross-current flows 282,284 that mix over the length of the manifold zone 286 via gaps 285 individing wall 287. This cross-flow mixing reduces momentum biased flowinto the connecting channels. The mixing can be a single component, twoor more reactants, or two phases. In the illustrated embodiment, thein-flows are coplanar; however, it should be appreciated that mixingcould alternatively or additionally be accomplished through holes in thesheet above or below the manifold.

As illustrated in FIG. 29, a manifold can be inclined to change thecross-sectional area of the manifold in the direction of flow, whichchanges the local connecting channel interface to manifold area ratioand the channel M2M manifold aspect ratio. By “inclined” is meant thatthe height (not merely the width) of the manifold varies. Preferably,the manifold slopes upward so that the smallest volume is adjacent tothe connecting channel furthest downstream (i.e., the opposite of theslope in FIG. 29). This structure can be made by etching.

In some embodiments, the gates from the manifold to the connectingchannels can be angled. This is schematically illustrated in FIG. 30. Anangled opening can be made by etching. The angled flows can add orsubtract from turning loss resistance and can be designed to make flowmore equal through the connecting channels. Here, “angled” means thatthe gate is sloped such that the center line through the gate forms anangle between 2 and 98 degrees or between 92 and 178 degrees, morepreferably between 20 and 80 or between 100 and 170 degrees with respectto the center line through the connecting channels. Preferably, thedesign is as illustrated where at least one channel (or preferably more)that is in the upstream section of the manifold is angled to reduceturning loss (with flow) while at least one channel (or preferably more)that is in the downstream section of the manifold is angled to increaseturning loss (against flow).

FIG. 31 illustrates an exploded (or preassembly) view of stackedconnecting channels that include an offset region 312 that allowsinterchannel mixing. In an offset configuration, a channel wall or wallsin a first layer extend to provide a fluid pathway into a secondadjacent layer.

Another option to reduce the effects of flow momentum is to placebaffles within the headers (not shown).

FIG. 32 illustrates an alternative form of gate in which porous bodiesare placed between a manifold 322 and connecting channels. Preferablyfor a header manifold for a Z-manifold or L-manifold the porous bodiesare arranged such that the greatest resistance to flow is present in theporous body 324 furthest downstream relative to the manifold while therelatively less resistance to flow is present in upstream porous body326 for a header manifold with a Mo value greater than 0.05. This putsthe highest flow resistance for the zone with the highest staticpressure value in the manifold, a product of increasing static pressurefrom momentum compensation. A header for a U-manifold with a Mo valuegreater than 0.05 may want the order reversed from that described forthe Z-manifold and L-manifold headers to compensate for momentumcompensation and friction losses in the footer. More generally, it ispreferred that a porous body with a relatively greater resistance toflow is located downstream in the header manifold relative to a porousbody with a relatively lesser resistance to flow for a header manifoldfor a Z-manifold or L-manifold. The reverse is true for the U-manifold.For flow distribution through connecting channels of equal width, atleast 3 porous bodies increase in flow resistance with increasingdistance downstream in the manifold. The porous bodies can be catalytic(e.g. in a reactor) or noncatalytic. A foam is a preferred example of aporous body.

FIG. 33 illustrates an embodiment in which flow is affected by aflexible projection 332 through a channel wall. The flexible projectioncan project from one side of a wall or through a channel wall and intoboth adjacent channels.

Multiple microdevices 3402, 3404, each with an internal micro-to-macromanifold may be further connected together with a macromanifold 3405(see FIG. 34A) to achieve any desired capacity or productivity. Thislevel of manifolding may comprise pipes or ducts that connect streamsbetween microdevices. At least one stream can be in a single pipe 3406or duct with an inlet 3407 or outlet 3408 to each parallel microdevice.In some embodiments, all streams are connected with a unique pipe orduct. In one embodiment, one or more outlet streams 3409 vents to theatmosphere, such as the case of a combustion exhaust stream.

The pipes or ducts that connect multiple microdevices preferablymaintain a hermetic seal around the respective inlet or outlet of afluid stream for each microdevice. The hermetic seal may be achieved bywelding or gasket connections. For a microdevice with multiple inlets oroutlets, the connecting macromanifold pipes or ducts may be connected toeach other but in a gas-tight manner to prevent cross-stream leaks orconnections. As an example, an inner pipe that contains the inlet forone stream, may contain an outer pipe that is attached to the inner pipearound a portion of the circumference of the inner pipe (not shown).Multiple pipes or ducts may be connected in this manner. An advantage ofthis approach includes a reduced amount of metal weight for themacromanifold, control of the thermal profile along the pipes to reducestress imposed material thickness limits, and reduced total volumerequired for the macromanifold system.

The macromanifold represents the first level of flow distribution. Flowenters from a single source and is distributed to two or moremicrodevices. After flow enters each microdevice it is furtheroptionally segregated into multiple submanifolds. From each submanifold,flow may be further distributed to multiple connecting channels.Finally, an optional embodiment includes a further level of flowdistribution to multiple subchannels within each microchannel. Eachsubchannel may take the form of a fin (either inserted or formedintegrally to the device) or other flow distributor housed within amicrochannel. There may be three, four, or more levels of flowdistribution required for the operation of microdevices that produce aquality index factor of less than 30%, or any of the preferred Q valuesdiscussed herein.

Flow Distribution in Two Dimensions

Where there is a need to distribute flow to two-dimensional array ofconnecting channels, in the stacking direction and in the planes ofchannels, often there are options that allow for using a single manifoldfor distribution. These single manifolds can be large ducts or pipes,and they are often used for cross-flow applications. For these cases,the frictional losses play a smaller role as the length of the manifoldover hydraulic diameter becomes small (L/D˜1). However, the momentumdriven phenomena, the momentum compensation and turning losses, becomethe main driving force for flow distribution and should be accounted forwithin the design. The manifold physics change from those of the highM2M manifold aspect ratio channel terms discussed in the one dimensionalmanifold section. The less significant turning losses for the highaspect ratio channel is due to the cross-sections of large ducts thathave square perimeters or have pipe or half-pipe perimeters. The turninglosses for these cases have less wall shear stress than seen for thehigh aspect ratio rectangular channels. The next two concepts describemeans of improving flow distribution to two dimensional channel arrays.

One problem with flow distribution is maldistribution through aconnecting channel matrix due to the momentum of incoming flow. Acentral feed inlet and central feed outlet can lead to channelingthrough the center of the matrix, as seen in cross-flow heat exchangers.See Lalot et al, Applied Thermal Engineering, v. 19, pp. 847-863, 1999;Ranganayakulu and Seetharamu, Heat and Mass Transfer, v. 36, pp.247-256, 2000).

Also, a single inlet tangent to the direction of flow can result in astream that distributes the bulk of the flow to the channels opposite tothe inlet and could induce large recirculation zones in the header andfooter, recirculation from the header to the footer and recirculation orstagnant zones in the device.

A device that ameliorates these problems is illustrated in FIG. 34Bwhich is a top-down view inside a channel in a device having multipleinlets 3406 parallel to the direction of flow. In the illustrateddesign, inlet flow is introduced from both sides of a sub-manifold 3402.If flow is introduced from only one side, the bulk of the flow wouldleave via the header inlet farthest from the main inlet. A simulationindicated that that this arrangement was successful in eliminatingrecirculation zones, recirculation from the footer to header andstagnant areas in the device. The basic distribution for this option isbiased to the center but to a greatly reduced extent as compared toother options.

Also illustrated in FIG. 34B are optional flow directors 3404 that candirect flow through a chamber. These flow directors can be louvers (orpaddles) that can be collectively or individually rotated to direct flowin a desired direction. A louver system was designed where all of thelouvers are attached together by an adjoining rod, which will allow allof the louvers to move and rotate at the same time, same direction andto the same position. The use of louvers provides a convenient way ofchanging flow directions within a device. The louvers are able to shiftthe flow such that it can be biased to the left, middle and right. Thus,in one example, the flow directors are rotatable louvers.

In some preferred embodiments, a heat exchange fluid is passed throughthe chamber with the heat exchange fluid biased. Stacked adjacent to theillustrated heat exchange chamber, either above and/or below, is areaction chamber (not shown) in which reactants pass in a cross-flowrelationship relative to the heat exchange fluid. This orientation isadvantageous if the reaction rate is greatest at the front or back ofthe reaction chamber and this high-reacting-rate portion is matched tothe biased flow through the heat exchanger such that the highest flow ofheat exchange fluid is directly adjacent to the highest reaction rate inthe adjacent reaction chamber.

Flow Distribution Plates

In some multichannel design embodiments, at low flow rates, frictionlosses may dominate causing flow to primarily pass through the center ofa multichannel array. One solution to this problem is to place a flowdistribution plate prior to a multichannel array. This concept isillustrated in FIG. 35 which shows flow being forced to the periphery ofa distribution plate 3502. Generally, this can be accomplished by aplate with orifices preferentially distributed nearer the periphery ofthe plate than to the center. Preferably, a second orifice plate 3504with a two-dimensional array of equally distributed holes follows thefirst plate. The combination of the first and second plates, preferablyin further combination with an open redistribution zone (not shown)following the first plate, equalizes pressure over the front surface ofan array and reduces flow maldistribution through a multichannel array.A partially exploded view of a multichannel device using the combinationof first and second flow redistribution plates 3602, 3604 is shown inFIG. 36.

Cross sectional and side views of another design with first and secondflow distribution plates is illustrated in FIG. 37. In this design, thefirst orifice plate 3702 has differing gate sizes to control flow. Thevarying gate sizes can either be used to equalize flow, or to provide anonuniform flow for instances in which nonuniform flow is desired. Inthe cases when local flow maldistribution (within the segment) wouldoccur using one orifice plate, for example, if the frictional loss istoo small in the microchannels (too short of a channel) or velocity inthe orifice is very high, a second orifice plate 3704 with a number oflarge orifices offset from the orifice position of the first plate(i.e., nonaligned) is needed to divert the flow stream from the singleorifice and ensure a uniform distribution within the segment ofmicrochannels (i.e., connecting channel matrix 3706). In someembodiments, because of the difference in turning losses, equal flow canbe obtained with a portion 2710 of the connecting channel matrix indirect contact with the manifold 3708 without intervening orificeplates.

In some embodiments, plates containing one or more orifice are disposedwithin the header. See FIG. 38. In the illustrated device, plates 3802with one or more orifices are of a shape that fits in the header crosssection and can be mounted (sealed or welded) inside the header so as toseparate the header of a microchannel device into several segments. Theorifice sizes are designed according to the desired flow rate andpressure drop for the corresponding group (arrays) of the microchannelsto realize a designed stepwise profile of flow rate and pressure dropover the whole device. As the pressure varies from segment to segment,the segment-averaged flow rate in the microchannels can be differentfrom segment to segment or can also be the same for a uniform flowdistribution. The illustrated design contains 6 microchannels withineach segment; however, it should be realized that any number of channelsmay be present in a segment, for example, in some preferred embodiments,2 to 100 channels, and in some embodiments 10 to 50 channels. Theillustrated design has orifice plates with decreasing orifice sizes inthe direction of flow to compensate for momentum and provide more equalflow through the connecting channels. The illustrated plates areparallel to the connecting channels. By selecting the number of orificeplates, the orifice size or number, the flow rate difference between themicrochannels of a single segment can also be designed and limitedwithin an allowable range. As such, a stepwise flow distribution can beachieved. As one example, if the illustrated layer were a coolant layerin an integrated reactor containing an adjacent reactor layer (notshown) in cross-flow relationship, coolant flow is concentrated in thearea immediately adjacent to the front (hottest part) of the reactorlayer.

Orifice plates can have equally distributed orifices of similar oridentical sizes, monotonically increasing or decreasing open areas, orcan be designed with any desired orifice distribution. For example, FIG.39A shows orifice plates with holes or slots that increase to a maximumarea then decrease down their length. In general, a moveable orificeplate between a manifold and connecting channels can be used to varyflow rate into connecting channels. For example, the plates in FIG. 39Bhave optional screw holes 392 for use as moveable plates. As shown inthe A-A view, the orifice plate can be moved up or down to vary flow.The plate can be mounted and sealed between the header of the device andthe channel inlet face using screws. When a flow distribution profilechange is needed, the relative position between the plate and thechannels can be changed by unscrewing the plate and moving the plate toa position corresponding to the designed new distribution profile. Thus,different flow distribution profiles within the same device can beobtained, and flow rates optimized for varying conditions.

Device Fabrication

Sheets and strips for forming laminated devices can be formed byprocesses including: conventional machining, wire EDM, plunge EDM, lasercutting, molding, coining, water jet, stamping, etching (for example,chemical, photochemical and plasma etch) and combinations thereof. Forlow cost, stamping to cut apertures through a sheet or strip isespecially desirable. Any shaping or forming process can be combinedwith additional steps. Some of the inventive methods can also becharacterized by the absence of certain forming techniques; for example,some preferred methods do not utilize etching, casting, melting apowder, molding, chemical or physical deposition, etc.

To form a laminated device, a sheet or strip is stacked on a substrate.For purposes of the present invention, a substrate is broadly defined toinclude another sheet or strip or a thicker component that could be, forexample, a previously bonded sheet stack. Preferably, multiple sheetsand/or strips are aligned in a stack before bonding. In someembodiments, a brazing compound is placed on one or more surfaces of asheet or strip (or plural sheets and/or strips) to assist bonding.Sheets and strips should be aligned in a stack. Alignment can beachieved by making sheets and/or strips with alignment apertures andthen using alignment pins to align the sheets and/or strips in a stack.A stack (including a subassembly that does not include all thecomponents of a final device) can be lifted from pins, or the pins canbe removed (such as by burning or by pulling out pins), or the pins canbecome bonded in the stack. Another alignment technique utilizes moldsfor aligning sheets and/or strips; this technique can be especiallyuseful for positioning flow modifiers such as ribs. In some embodiments,molds remain in place while the stack components are attached in placesuch as by welding, heating an adhesive, or diffusion bonding;subsequently, the molds are removed. In other embodiments, the mold canbe removed before the components are bonded. Molds can be reusable orcan be single use components that could be removed, for example, byburning out.

The sheets, strips and subassemblies may be joined together by diffusionbonding methods such as ram pressing or hot isostatic pressing (HIPing).They may also be joined together by reactive metal bonding, brazing, orother methods that create a face seal. Welding techniques, such as TIGwelding, laser welding, or resistance welding, may also be used. Devicescan alternatively be joined by the use of adhesives.

In cases where a full length seal is desired to provide fluidcontainment, seam welding can be employed to form a complete sealbetween a substrate, strip and/or flow modifier. Tack or spot weldingcan be used to hold strips, flow modifiers or subassemblies in place,without creating a complete seal along an entire edge. Usually, the tackwelded assemblies will be subjected to a subsequent bonding step.

Brazing techniques and compositions are known and can be employed informing devices of the present invention. Braze cycles longer than about10 hours can result in better devices that show less distortion and havebetter bonding.

Techniques for assembly and/or bonding of devices can use the sametechniques or a mixture of techniques. For example, a subassembly couldbe welded together and then welded to a second subassembly that itselfwas formed by welding. Alternatively, for example, a subassembly couldbe spot welded together, brazed to a second subassembly, and thecombined assembly diffusion bonded.

Numerous microchannel, laminated devices can be made with the componentsdescribed herein and/or structures described herein and/or made usingthe methods described herein. Such laminated devices can be, forexample, heat exchangers, reactors (integrated combustion reactors areone preferred type of reactor), separators, mixers, combinations ofthese, and other microchannel, laminated devices that are capable ofperforming a unit operation. The term “laminated articles” encompasseslaminated devices as well as laminated subassemblies.

While the individual laminae are quite thin, the device dimensions arenot particularly limited because numerous laminae (of a desired lengthand width) may be stacked to any desired height. In some preferredembodiments, the inventive articles contain at least 5 laminae, morepreferably at least 10, and in some embodiments, more than 50. In somepreferred embodiments, the articles contain at least 2, in someembodiments at least 5 repeating units (with each repeating unitcontaining at least 3 different laminae).

In some embodiments, at least one fluid is flowing through the manifold,and in some embodiments, this fluid is a gas. The header or footer canbe shaped to fit an end of a subassembly, for example a square end on aheader/footer to match one side of a cubic subassembly.

The articles may be made of materials such as plastic, metal, ceramic,glass and composites, or combinations, depending on the desiredcharacteristics. In some preferred embodiments, the articles describedherein are constructed from hard materials such as a ceramic, an ironbased alloy such as steel, or monel, or high temperature nickel basedsuperalloys such as Inconel 625, Inconel 617 or Haynes alloy 230. Insome preferred embodiments, the apparatuses are comprised of a materialthat is durable and has good thermal conductivity. In some embodiments,the apparatuses can be constructed from other materials such as plastic,glass and composites. Materials such as brazes, adhesives and catalystsare utilized in some embodiments of the invention.

The present invention may include chemical reactions that are conductedin any of the apparatus or methods of conducting reactions that aredescribed herein. As is known, the small dimensions can result insuperior efficiencies due to short heat and mass transfer distances.Reactions can be uncatalyzed or catalyzed with a homogenous orheterogeneous catalyst. Heterogeneous catalysts can be powders, coatingson chamber walls, or inserts (solid inserts like foils, fins, or porousinserts). Catalysts suitable for catalyzing a selected reaction areknown in the art and catalysts specifically designed for microchannelreactors have been recently developed. In some preferred embodiments ofthe present invention, catalysts can be a porous catalyst. The “porouscatalyst” described herein refers to a porous material having a porevolume of 5 to 98%, more preferably 30 to 95% of the total porousmaterial's volume. The porous material can itself be a catalyst, butmore preferably the porous material comprises a metal, ceramic orcomposite support having a layer or layers of a catalyst material ormaterials deposited thereon. The porosity can be geometrically regularas in a honeycomb or parallel pore structure, or porosity may begeometrically tortuous or random. In some preferred embodiments, thesupport of the porous material is a foam metal, foam ceramic, metal felt(i.e., matted, nonwoven fibers), or metal screen. The porous structurescould be oriented in either a flow-by or flow-through orientation. Thecatalyst could also take the form of a metal gauze that is parallel tothe direction of flow in a flow-by catalyst configuration.

Alternatively, a catalyst support could be formed from a dense metalshim, fin or foil. A porous layer can be coated or grown on the densemetal to provide sufficient active surface sites for reaction. An activecatalyst metal or metal oxide could then be washcoated eithersequentially or concurrently to form the active catalyst structure. Thedense metal foil, fin, or shim would form an insert structure that wouldbe placed inside the reactor either before or after bonding or formingthe microchannel structure. A catalyst can be deposited on the insertafter the catalyst has been inserted. In some embodiments, a catalystcontacts a wall or walls that are adjacent to both endothermic andexothermic reaction chambers.

The invention also includes processes of conducting one or more unitoperations in any of the designs or methods of the invention. Suitableoperating conditions for conducting a unit operation can be identifiedthrough routine experimentation. Reactions of the present inventioninclude: acetylation, addition reactions, alkylation, dealkylation,hydrodealkylation, reductive alkylation, amination, ammoxidationaromatization, arylation, autothermal reforming, carbonylation,decarbonylation, reductive carbonylation, carboxylation, reductivecarboxylation, reductive coupling, condensation, cracking,hydrocracking, cyclization, cyclooligomerization, dehalogenation,dehydrogenation, oxydehydrogenation, dimerization, epoxidation,esterification, exchange, Fischer-Tropsch, halogenation,hydrohalogenation, homologation, hydration, dehydration, hydrogenation,dehydrogenation, hydrocarboxylation, hydroformylation, hydrogenolysis,hydrometallation, hydrosilation, hydrolysis, hydrotreating (includinghydrodesulferization HDS/HDN), isomerization, methylation,demethylation, metathesis, nitration, oxidation, partial oxidation,polymerization, reduction, reformation, reverse water gas shift,Sabatier, sulfonation, telomerization, transesterification,trimerization, and water gas shift. For each of the reactions listedabove, there are catalysts and conditions known to those skilled in theart; and the present invention includes apparatus and methods utilizingthese catalysts. For example, the invention includes methods ofamination through an amination catalyst and apparatus containing anamination catalyst. The invention can be thusly described for each ofthe reactions listed above, either individually (e.g., hydrogenolysis),or in groups (e.g., hydrohalogenation, hydrometallation andhydrosilation with hydrohalogenation, hydrometallation and hydrosilationcatalyst, respectively). Suitable process conditions for each reaction,utilizing apparatus of the present invention and catalysts that can beidentified through knowledge of the prior art and/or routineexperimentation. To cite one example, the invention provides aFischer-Tropsch reaction using a device (specifically, a reactor) havingone or more of the design features described herein.

EXAMPLES Example 1 Comparative Calculated Example

Calculations have been conducted based on a design shown in FIGS. 51 to64 of Golbig published patent application US 2002/0106311A1. In thisdesign, a fluid flows into two separate headers of the same dimensions.The header intersects at a right angle with the ends of connectingchannels of varying widths; the widths varying from widest at the startof the header to the narrowest channel at the end. The object of thisdesign was to enable “viscous fluids to be processed in parallel fluidchannels with substantially equivalent residence time distributions.”The varying channel width tailors the connecting channel flow resistanceto compensate for the differences between the header and footer pressurefor a given fluid viscosity and flow rate, adding resistance to channelswith larger pressure difference driving forces and less resistance tothose with lower pressure difference driving force.

While the publication does not specifically describe all the dimensionsof the design, approximate dimensions can be surmised from the text.From paragraph 292, the shims have a thickness of 0.3 mm, and paragraph295 shows the relative channel widths in units which appear to be amultiplicative factor of channel height. Measuring channel widths fromthe figure, and comparing to the unit dimensions in paragraph 295, wecalculate that 0.1 cm of measured distance is equal to 0.393 mm in thedesign. Similarly, the connecting channel lengths are measured to be13.8 cm, correlating to an actual design length of 54.3 mm, with ribsbetween channels of 0.59 mm, header width of 0.39 mm, and footer widthof 2.55 mm. In paragraph 138 it is stated that limiting openings to amaximum of 2 mm enhances the bonding process—this limit is consistentwith our calculated range of channel openings. The preferred embodimentof this invention is desired to have substantially equivalent residencetimes.

Golbig et al. use an analogy to circuit theory, and use the laminar flowregime to describe flow. Thus, we calculate pressure drop as

$\begin{matrix}\begin{matrix}{{\Delta \; P} = {\frac{4\; {fL}}{D}\frac{G^{2}}{2\; \rho}}} \\{= {\frac{4\; L}{D}\left( \frac{C}{Re} \right)\frac{G^{2}}{2\; \rho}}} \\{= {\frac{4\; L}{D}\left( \frac{\mu \; C}{GD} \right)\frac{G^{2}}{2\; \rho}}} \\{= {\left( \frac{2\; \mu \; {CL}}{D^{2}} \right)\frac{G}{\rho}}} \\{= {\left( \frac{2\; \mu \; {CL}}{D^{2}} \right)U}}\end{matrix} & (20)\end{matrix}$

whereC [dimensionless]=Coefficient, a function of channel dimensions andperimeterf [dimensionless]=C/Re=Fanning friction factorD [m]=Hydraulic diameter=4(cross-sectional area)/(channel perimeter)L [m]=length of channelG [kg/m²/s]=Mass flux rateρ [kg/m³]=DensityRe [dimensionless]=Reynolds number=GD/μ.U [m/s]=Mean channel velocityμ [kg/m/s]=Dynamic viscosity of the fluidThe resistance for any section becomes

$\begin{matrix}{R = \frac{2\; \mu \; {CL}}{D^{2}}} & (21)\end{matrix}$

The equation (1.3) assumes fully developed laminar flow, meaning theboundary layer in the channel has fully developed over the channellength L. Using the definition of dimensionless hydrodynamic length x⁺,

$\begin{matrix}{x^{+} = \frac{L}{D\mspace{11mu} {Re}}} & (22)\end{matrix}$

the flow is approaching fully developed flow around a x⁺ value of 0.05,and is much closer to developed flow at a x⁺ value of 1¹. If resistancepath lengths L are small, either the hydraulic diameter D or Re mustbecome small to get reasonable x⁺ values. To meet the limitation ofx⁺>0.05 to 1 for given channel hydraulic diameters, we will look at lowReynolds number values. ¹ R. K. Shah and London, A. L. “Advances in HeatTransfer. Supplement 1. Laminar flow forced convection in ducts—A sourcebook for compact heat exchanger analytical data.” Academic Press, NewYork, 1978, p. 212.The system we used for analysis has the same dimensions as describedabove, with the following assumptions and factors:

-   -   Two header inlet mass flow rates of equal flow rate, and the        distributions of the two headers are assumed to be the same.    -   The reactant streams have the mass flux rates from the header,        while the product stream mass flux rate have the combined flow        of the two header inputs for channel i

2G _(react) [i]=G _(prod) [i]  (23)

-   -   Ignore the pressure drop losses in the transitions for the        streams between shims and on mixing, as the first will be a        small addition and the latter because the stream momentums are        so low.    -   Use air at room temperature (20° C.) and have the footer outlet        at 101325 Pascals [Pa] or 1.01325 bar. Golbig's preferred        process doesn't specify a specific temperature rise or species        change, so we are arbitrarily setting the conditions.    -   Quality index factor will be based upon mass flux rates with the        Q₂ equation

$Q_{2} = {\frac{G_{\max} - G_{\min}}{G_{\max}} \times 100\%}$

-   -   The system had two options for the header laminar Fanning        friction factors f,        -   Fully developed flow        -   Developing flow, with the L in the x⁺ equation (0.17) based            on the distance away from the entrance in the header and the            distance from the beginning of the manifold in the footer.            The first case that was investigated was for a flow rate of            10⁻⁰⁶ kg/s flow to each header, with fully developed flow in            the manifolds, and all turning losses and momentum            compensation effects removed. The channel mass flux rates            for the case are plotted in FIG. 40. The Q₂ factor is almost            71%. The mass flux rate varies from 0.2 to 0.6 kg/m²/s in            the channels, with flow favoring the first (i.e. widest)            channels. The header and footer Mo values are on the order            of 0.04 and 0.03, respectively. The pressure drop for the            system was on the order of 350 Pa (3.5×10⁻³ bar) and the            header inlet and footer outlet Reynolds numbers were 159 and            78, respectively. When the momentum compensation, turning            losses and laminar developing flows are added, we get worse            results, as seen in FIG. 41.

As mentioned in the published application, the system dimensions are afunction of the viscosities of the reactants and the products of thereaction system. The case with water at the same mass flow rate was runand the results in FIG. 42 show the results are just as poor.

Doing some optimization of header and footer widths, the Q factor comesdown to 7% by setting the header and footer manifold widths to 0.004 mmand 0.003 mm, respectively. The results are shown in FIG. 43. The Movalues for the header and footer are low, on the order of 0.01. When theflow rates for this case are increased 10 fold to 10⁻⁰⁵ kg/sec perheader manifold, the performance drops precipitously in Q factor, asseen in FIG. 44. The Q factor increases to 33%, and the results showtypical Z-manifold behavior for high momentum flows: higher flux rate atthe last connecting channel in the header compared to the first channel.Note that the header and footer Mo values are higher than 0.05, despitelow Reynolds numbers. Thus, turbulent Reynolds numbers are not requiredto have a high Mo value—high Mo can occur in low laminar flow.

The methodology in Golbig's patent application doesn't show equal flowdistribution (low Q) for fully developed laminar flow at low headvalues, much less so at higher heads that lead to substantial manifoldturning loss and momentum compensation terms. The reason may be therelationship between channel flow resistance and the degree to which theconnecting channel's aspect ratio leads to that resistance. This isshown in Examples 4 and 5.

Example 2

This example describes the predicted performance of the SMR module flowdistribution discussed earlier in the application.

In this design, the gate widths grow wider as the length of asub-manifolds upstream length increases, and the width of a sub-manifoldincreases as the sub-manifolds upstream length increases. By using thewidths of both sub-manifolds and gates within sub-manifolds, the overallpressure drop seen in each sub-manifold was equalized in both air andfuel header M2M manifolds. The sub-manifold with the shortest pathlength (#1) across the shim has the thinnest sub-manifold width and thethinnest gates, while the sub-manifold with the longest path across theshim (#6) has the widest sub-manifold width and widest gates. Therelative dimensions for the manifolds are given below in Table 1.

TABLE 1 Dimensions for the combustion M2M air and fuel sub-manifoldslisted per sub-manifold number. Gate number is given in the order thatthe manifold stream sees the gate, i.e. #1 for the first gate seen inthe sub-manifold and #3 for the last gate seen. Sub- M2M Width of airWidth of Fuel manifold channel Gates (inches) Gates (inches) numberwidth (in) #1 #2 #3 #1 #2 #3 1 0.400 0.188 0.175 0.172 0.105 0.102 0.0942 0.500 0.165 0.167 0.167 0.122 0.119 0.103 3 0.500 0.240 0.235 0.2320.143 0.142 0.127 4 0.550 0.260 0.260 0.260 0.160 0.161 0.145 5 0.6000.277 0.277 0.277 0.299 0.230 0.152 6 0.600 0.590 0.580 0.588 0.5600.555 0.550As fluid leaves the sub-manifolds distribution zone into the gates, theconstant width of the section leads to a static pressure increase tocompensate the loss of dynamic pressure, minus whatever frictionallosses occur in that zone. With each gate, the static pressure has thepotential to increase or stay steady in this high momentum (dynamicpressure) flow, but the turning losses aren't constant over themanifold. The use of gate widths, such as in Table 1, allow us to tailorthe local pressures in the device for better flow distribution. Ingeneral, decreasing the gate width with increasing gate number in asub-manifold overcomes the momentum compensation factors in the header.FIGS. 45 and 46 show the model results for the header and gate staticpressures plotted versus the gate number (18 total per manifold) for airand fuel respectively. The lower number gates add additional backpressure to compensate for shorter upstream manifold lengths. The use ofthe gates achieves an even pressure at the gates across the module,equalizing the pressure drop driving force to the exhaust outlet at 0.25psig. The DPR3 ratios for both fuel and air manifolds are high for gatesone through three in the first sub-manifold, but the average value isabout 0.5 because the turning losses decrease as the sub-manifold numberincreases.

Results of the coupled combustion manifold are seen in FIG. 47, showingthe model predictions of the 72 channel flow rates for air and fuelplotted versus the fuel channel number. The overall results are listedbelow.

Total air M2M mass flow rate: 14.96 kilograms per hourTotal fuel M2M mass flow rate: 4.84 kilograms per hour (Natural gas andair)Total air M2M quality index factor: 3.9%Total fuel M2M quality index factor: 6.1%Air M2M sub-manifold to sub-manifold quality index factor: 0.2%Fuel M2M sub-manifold to sub-manifold quality index factor: 0.5%Inlet air M2M pressure (including turning loss from macro manifold):8.16 psigInlet fuel M2M pressure (including turning loss from macro manifold):6.61 psig

Example 3

This example is a calculated example based on a sub-manifold that hasthe following features: L-manifold header, like that described; constantwidth, height of M2M manifold; 3 “gates”, each serving four connectingchannels downstream of the distribution section; and high momentum flow(Entrance Mo=0.7>>0.05). The conditions are: an outlet pressure of 1 atm(101325 Pa); air flow of 38.22 SLPM; and 20° C.

The header M2M manifold dimensions are:

-   -   0.041″ height, made from a 0.017″ and a 0.023″ shims and a        0.001″ tall gasket    -   0.400″ wide for the entire manifold (W_(m))    -   A_(M)=1.04×10⁻⁵ m²    -   Lengths:        -   From macro manifold connection to first gate: 1.250″            (=L_(u,1))        -   From macro manifold connection to end of the manifold 3.700″        -   Lengths for friction losses:            -   L_(c,1)=0.270″            -   L_(c,2)=0.250″            -   L_(c,3)=0.245″            -   L_(u,1)=1.250″            -   L_(u,2)=0.680″            -   L_(u,3)=0.692″                Gate and distribution section dimensions:    -   Center position of gates from macro manifold:        -   1^(st): 1.410″        -   2^(nd): 2.350″        -   3^(rd): 3.290″    -   Gate channel height: 0.024″    -   Length of gate opening in flow direction: 0.060″    -   Gate widths:        -   1^(st): 0.270″ (A_(c,1)=0.0000041 m²)        -   2^(nd): 0.250″ (A_(c,2)=0.0000039 m²)        -   3^(rd): 0.245″ (A_(c,3)=0.0000038 m²)    -   Dimensions of each gate downstream distribution section:        -   Length: 0.500″        -   Height: 0.040″ total-0.017″ is in the open “picture frame”            shim        -   Width: 0.820″    -   Connection to downstream connecting channels        -   Through the 0.024″ wide channel        -   0.060″ total length to connecting channel            Connecting channel dimensions    -   Twelve channels, 0.160″ wide    -   Four channels per gate, each separated by 0.060″ wide ribs (3        per gate)    -   Two 0.120″ wide ribs separating the channels (2 total)    -   2.700″ wide connecting channel matrix    -   Heights and widths        -   For 1.000″ downstream of the gate distribution section            -   0.041″ channel height            -   A_(cc)=0.0000042 m²        -   For the last 11.500″ of the channel            -   0.018″ channel height            -   A_(cc)=0.0000018 m²    -   The channel flows end abruptly, exiting out to ambient pressure.

Equations:

Same as described in the Discussion section, but with the followingadditions to the downstream resistance. The gate distribution sectionhas a resistance term for each of the four downstream channels,dependent upon gate Reynolds number. The gate has a mass flow ratecontinuity equation to distribute the flows. The connecting channelpressure drop has two major resistances: friction losses for the1.000″long section downstream of the gate; friction losses for the last11.500″ of the channel; and the sudden contraction losses and the exitlosses are ignored.

Results:

FIG. 48 shows the mass flow rates in each connecting channel. Thepredicted quality index factor Q₁ is 2.2%. FIG. 49 shows the predictedpressures in the header and the gates across the manifold. The headerpressure profile shows the effect of frictional losses over the first1.25″ inches prior to the first gate, with the Reynolds number in the8000 range (turbulent). The static pressures climb from the beginning ofeach gate (lower position value) to the end of the gate, despitefriction losses. There are friction losses in the header between gates.The use of decreasing gates cross-sectional area in the direction offlow in the header to compensate for the changes in the header staticpressure leads to the good distribution from gate to gate. FIG. 49 showsthe pressure profile from Example 3 in the header (round dots) and inthe gates (squares) plotted versus position from the inlet of thechannel.

The gate turning losses are needed to compensate for the pressureprofile created by the changes in flow regime. At the first gate theupstream and downstream Reynolds numbers are 8054 and 5386,respectively, well into turbulent flow regimes. The static pressureincrease for the first gate in that section is dramatic, 1600 Pa, makingup for the friction losses of the channel up to that point. The secondgate has upstream and downstream Reynolds numbers of 5386 and 2699,which start in the turbulent range and drop into the transition range.The pressure gain at the second gate is 400 Pa, a substantial drop fromthe turbulent case. The third gate has upstream and downstream Reynoldsnumbers of 2699 and 0, which implies the flow starts in the transitionflow range and end in laminar range. The pressure gain at the third gateis on the order of 160 Pa, a substantial drop from the second and firstgate's static pressure gains of 400 Pa and 1600 Pa, respectively. Thisexample shows that the effect of momentum compensation on the staticpressure profile, and in turn illustrates the need to use turning lossesto equalize the pressures across the gates. It also illustrates the highflow rates needed to supply millisecond contact time microchannelreactors can lead to very large Reynolds numbers in the M2M manifoldwhen multiple channels must have high overall flow rates that are in thetransition and turbulent ranges. These flow regimes have large headvalues that give rise to substantial momentum compensation and turningloss terms, as this example shows.

Example 4 M2M Patent—Manifold Performance Comparison

In the following discussion, inventive manifolds are compared withdesigns of the type disclosed by Golbig et al. in WO 03/043730 A1. Themanifold options for a L-manifold with a 72 connecting channel matrixwere evaluated using a manifold design tool. The three options were asfollows: a manifold split into sub-manifolds with gate connectingchannel interfaces, a grate design with one large manifold width andconstant channel opening and channel matrix dimensions, and a gratedesign with one large manifold width and channel widths varying fromchannel to channel (like those discussed in Golbig et al). All thedesigns had the same inlet mass flow rate and target mass flux ratedistribution (akin to contact time). Some results follow:

The sub-manifold design using variable width gates for sub-manifold flowdistribution had the lowest quality index factor (Q₁=6.03%), but had arelatively high manifold pressure drop over inlet head ratio (8.8) dueto the gate M2M turning losses. The pressure drop was estimated at 3.25psid from the macro manifold to the outlet. The final width of themanifold was 3.45″, with 3.15″ actual open space. It is possible tofurther improve this design for lower quality index factors.

The option of a grate design with a single M2M manifold and constantconnecting channel width dimensions had poor quality index factors formost gate widths, obtaining values of Q₁=41.08% to 29.03% for M2M widthsof 2.5 inches to 3.5 inches.

The third option was a grate design with a single M2M manifold with theoption of varying the connecting channel width as that used by Golbig etal. This design was not able to match the low quality index factor ofthe sub-manifold and gate design. It reached a low of Q₂=12.8% with a2.00″ wide manifold, which greatly lowered the manifold pressure drop tohead ratio down to 3.9. Large changes in channel width are needed toobtain reasonable control, i.e. large values of Ra were needed to obtaingood flow distribution.

Common Manifold Features

There are 72 channels, whose total width must add up to 11.52″(=72×0.160″) The walls (i.e ribs) in between the channels make the totalmanifold length add up to 16.800″. The matrix channels are 0.017″ inheight, while the manifold-to-connecting channel opening is 0.023″tall.In between these two zones there is a short length 0.040″ tall. There isa 1″ long zone upstream of the manifold and all systems have a commonmacro-to-M2M turning loss. All manifold sections have a total height of0.040″ (1.016 mm) The grate systems assume a 0.023″ zone (shim) liesbeneath the 0.040″ tall manifold section, with the grate extendingacross the entire M2M manifold width. A total of 0.00494 kg/second ofair was sent through all three systems at 20° C., with an outletpressure of 101.325 kPa.

Sub-Manifolds with Gate System

The sub-manifold system dimensions, both M2M channel widths and gatewidths, are given in Table 1.

TABLE 1 The sub-manifold and gate design dimensions. M2M Sub- channelmanifold width Width of Gates (inches) number (in) #1 #2 #3 1 0.4000.270 0.250 0.245 2 0.500 0.272 0.255 0.251 3 0.500 0.352 0.330 0.325 40.550 0.390 0.363 0.358 5 0.600 0.368 0.349 0.342 6 0.600 0.580 0.4400.430The resulting manifold parameters for this case are: The height of theM2M channel (h_(M2M)) is 1.016 mm. The total length of the manifold is16.800″ in total, and each L_(M2M) value is 2.700″ for eachsub-manifold. The ratio of the length of the channels between the end ofthe gate and the 11.5 inch long section to L_(M2M) is 0.23-1.66, basedupon sub-manifold lengths. The sub-manifold Mo values ranged from 0.70to 0.77. The Q₁ values for the connecting channel and sub-manifolds are6.0% and 0.3%, respectively. The Ra value for the system's gates are2.36 and the manifolds pressure drop is 8.83 times its inlet head.The Grate with Constant Channel Widths

Performance was calculated with all channel widths set to 0.160 inch.The results are shown in Table 2. The table shows improvement in thequality index factor with increasing channel width, but the overall Qfactors are very large. The major driving force for the poordistribution is the turning losses from the M2M manifold to thechannels. These turning loss values are large at the entrance of themanifold due to the large flow rates seen there, adding substantial flowresistance to these channels. This in turn causes flow to skew to thechannels at the end of the manifold.

TABLE 2 Constant channel width results for various manifold widthsManifold Quality index Width factor Q Manifold pressure drop (inches)(%) Over inlet head ratio Mo value 2.50 41.08 5.886 0.141 2.75 37.955.983 0.137 3.00 34.82 6.064 0.134 3.15 33.12 6.102 0.132 3.25 31.856.131 0.131 3.50 29.03 6.191 0.128Grate Design with Channel Widths Varying from Channel to Channel

Channel widths distribution added up to a total width of 11.52 inches oftotal channel width. Basing the channel width on channel number i

$\begin{matrix}{{{Width}\;\lbrack i\rbrack} = {M + {L\left\lbrack \frac{{i - 36.5}}{36.5 - 1} \right\rbrack}^{B}}} & (1)\end{matrix}$

where M is the median channel width value, L [inches] is the offset fromthe medium width, i is the channel number, and B is the power factor forchanging the channel distribution. L is positive for i≦36 and negativefor i>36. This equation (11) allows the distribution to be varied fromlinear to various curves from the median value of 0.160″.

The results are shown in Table 3 for various M2M channel widths. Aninteresting trend appears—as the M2M channel width decreases, bettercontrol of the streams is obtained, up to a minimum value of about2.00″. This is due to the larger connection to manifold cross-sectionalarea ratios (connection openings to manifold) seen at thinner M2Mmanifold widths. As the connection to manifold cross-sectional arearatio increases, the turning losses decrease in pressure drop. Thatcoupled with the relative decrease in connecting channel matrix flowresistance as the channels approach parallel plates for a set channelheight, the net effect is less resistance to flow for the first channelsin the system. FIG. 50 shows the mass flux rate distribution versuschannel position in the manifold for the best case at 2.0″ wide. Forsmaller M2M widths the momentum compensation static pressure increaseseroded the control that the changing width provided.

TABLE 3 Varying channel width results Quality Manifold Ratio of M2MIndex Pressure widest to Manifold Factor Drop Over thinnest Width M L Q₂Inlet head channels, (inches) (inches) (inches) B (%) Mo ratio Ra 1.750.160 0.100 0.50 16.83 0.156 3.7 4.3 2.00 0.160 0.120 0.50 12.77 0.1503.9 7.0 2.25 0.160 0.120 0.50 14.81 0.145 4.2 7.0 2.50 0.160 0.120 0.7517.35 0.141 4.5 7.0 2.75 0.160 0.120 0.75 18.79 0.137 4.7 7.0 3.00 0.1600.120 0.75 19.15 0.134 4.9 7.0 3.15 0.160 0.120 0.75 18.73 0.132 5.0 7.0The channel width distribution shown in the Ra ratio was high for all ofthe cases. To get a good distribution with changing channels widths, youwould need a large change in channel width. This may not be feasible forall processing cases or for fabrication of large numbers of thesemanifolds.In summary, the quality index factors, Ra and Mo ratios for the threecases discussed above are listed in Table 4.

TABLE 4 Summary of case comparison for the 72 channel L-manifoldConnecting channel quality index Case factor (%) Ra ratio Mo ratioSub-manifolds with varying gates Q₁ = 6.0%  2.4 0.74 widths and constantconnecting channel widths Single grate manifold with Q₁ = 29.0% 1.0 0.13constant connecting channel widths Single grate manifold with Q₂ = 12.8%7.0 0.15 varying connecting channel widths

Example 5

For a variable width connecting channel M2M manifold, what is therelationship between the connecting channel quality index factor Q₂ andthe Ra and pressure drop ratio? Based on the variable channel widthdesign shown in Golbig, WO 03/043730, Quality index factor wascalculated as a function of the ratio of the area of the largest to thesmallest channel (Ra) and two values of manifold pressure drop ratiodiscussed in the glossary section. While Example 4 was based upon afixed connecting channel length, the results shown below reflectchanging length which in turn changes the connecting channel backpressure. The results show the effect of channel width change upon flowdistribution as a function of channel back pressure.

FIG. 51 shows the minimum quality index factors, based upon thedimensions discussed in Example 4, plotted versus connecting channelpressure drop over manifold pressure drop.

The Ra=1 curve shows constant channel width Q2 values, and predictablyyou can achieve small Q₂ factors for this system as the pressure drop inthe channel increases. If the connecting channel pressure drop is largeenough, special manifold designs may not be necessary.

As the Ra value increases from unity the Q factors for the pressure dropratio increasing from zero fall to a minimum below the Ra=1 value. Thus,for a given back pressure, there may be a non unity Ra value that givesa better Q factor than the Ra=1 value

However, as values of the pressure drop ratio increase, the Q₂ curves ofconstant Ra cross over the Ra=1 curve and to asymptote to values higherthan the Ra=1 values. However, if the lengths of the channels of varyingwidth get long enough, a maldistribution will occur due to differingresistance in the channel flow resistance.

FIG. 52 shows the same quality index factor data plotted versus theratio of connecting channel pressure drop over the manifold inlet head,and while the curves change slightly, the general trends stay the same.The Q₂ surface in FIG. 2 based upon Ra and DPR₁ is made by the constantRa values correlations based on the curves in FIG. 52 and Lagrangianinterpolation between these values to get a representative curve of bestcases Q:

Q _(c)(Ra,DPR ₁)=E1+E2+E4+E6+E8+E10+E12,

where

${E\; 1} = {\frac{112.9 + {1.261{DPR}_{1}}}{\begin{matrix}{1 + {0.3078\; {DPR}_{1}} +} \\{0.003535\; {DPR}_{1}^{2}}\end{matrix}}\left\lbrack \frac{\begin{matrix}{\left( {{Ra}\text{-}2} \right)\left( {{Ra}\text{-}4} \right)\left( {{Ra}\text{-}6} \right)} \\{\left( {{Ra}\text{-}8} \right)\left( {{Ra}\text{-}10} \right)\left( {{Ra}\text{-}12} \right)}\end{matrix}}{\left( {1\text{-}2} \right)\left( {1\text{-}4} \right)\left( {1\text{-}6} \right)\left( {1\text{-}8} \right)\left( {1\text{-}10} \right)\left( {1\text{-}12} \right)} \right\rbrack}$${E\; 2} = {\frac{\begin{matrix}{91.73 - {1.571\; {DPR}_{1}} +} \\{0.01701\; {DPR}_{1}^{2}}\end{matrix}}{\begin{matrix}{1 + {0.2038\; {DPR}_{1}} +} \\{0.00193\; {DPR}_{1}^{2}}\end{matrix}}\left\lbrack \frac{\begin{matrix}{\left( {{Ra}\text{-}1} \right)\left( {{Ra}\text{-}4} \right)\left( {{Ra}\text{-}6} \right)} \\{\left( {{Ra}\text{-}8} \right)\left( {{Ra}\text{-}10} \right)\left( {{Ra}\text{-}12} \right)}\end{matrix}}{\left( {2\text{-}1} \right)\left( {2\text{-}4} \right)\left( {2\text{-}6} \right)\left( {2\text{-}8} \right)\left( {2\text{-}10} \right)\left( {2\text{-}12} \right)} \right\rbrack}$${E\; 4} = {\frac{\begin{matrix}{24.27 - {4.943\; {DPR}_{1}} +} \\{0.3982\; {DPR}_{1}^{2}}\end{matrix}}{\begin{matrix}{1 - {0.2395\; {DPR}_{1}} +} \\{{0.03442\; {DPR}_{1}^{2}} -} \\{0.000006657\; {DPR}_{1}^{3}}\end{matrix}}\left\lbrack \frac{\begin{matrix}{\left( {{Ra}\text{-}1} \right)\left( {{Ra}\text{-}2} \right)\left( {{Ra}\text{-}6} \right)} \\{\left( {{Ra}\text{-}8} \right)\left( {{Ra}\text{-}10} \right)\left( {{Ra}\text{-}12} \right)}\end{matrix}}{\left( {4\text{-}1} \right)\left( {4\text{-}2} \right)\left( {4\text{-}6} \right)\left( {4\text{-}8} \right)\left( {4\text{-}10} \right)\left( {4\text{-}12} \right)} \right\rbrack}$${E\; 6} = {\frac{29.23 - {2.731\; {DPR}_{1}} + {0.09734\; {DPR}_{1}^{2}}}{1 - {0.1124\; {DPR}_{1}} + {0.005045\; {DPR}_{1}^{2}}}\left\lbrack \frac{\begin{matrix}{\left( {{Ra}\text{-}1} \right)\left( {{Ra}\text{-}2} \right)\left( {{Ra}\text{-}4} \right)} \\{\left( {{Ra}\text{-}8} \right)\left( {{Ra}\text{-}10} \right)\left( {{Ra}\text{-}12} \right)}\end{matrix}}{\begin{matrix}{\left( {6\text{-}1} \right)\left( {6\text{-}2} \right)\left( {6\text{-}4} \right)} \\{\left( {6\text{-}8} \right)\left( {6\text{-}10} \right)\left( {6\text{-}12} \right)}\end{matrix}} \right\rbrack}$ ${E\; 8} = {\frac{\begin{matrix}{25.98 + {11.26\; {DPR}_{1}} +} \\{{0.02201\; {DPR}_{1}^{2}} + {0.5231\; {DPR}_{1}^{3}}}\end{matrix}}{\begin{matrix}{1 - {0.8557\; {DPR}_{1}} +} \\{{0.00887\; {DPR}_{1}^{2}} + {0.02049\; {DPR}_{1}^{3}} -} \\{0.000002866\; {DPR}_{1}^{4}}\end{matrix}} \times \left\lbrack \frac{\begin{matrix}{\left( {{Ra}\text{-}1} \right)\left( {{Ra}\text{-}2} \right)\left( {{Ra}\text{-}4} \right)} \\{\left( {{Ra}\text{-}6} \right)\left( {{Ra}\text{-}10} \right)\left( {{Ra}\text{-}12} \right)}\end{matrix}}{\begin{matrix}{\left( {8\text{-}1} \right)\left( {8\text{-}2} \right)\left( {8\text{-}4} \right)} \\{\left( {8\text{-}6} \right)\left( {8\text{-}10} \right)\left( {8\text{-}12} \right)}\end{matrix}} \right\rbrack}$ ${E\; 10} = {\frac{\begin{matrix}{20.75 - {3.371\; {DPR}_{1}} +} \\{{0.9026\; {DPR}_{1}^{2}} + {0.01277\; {DPR}_{1}^{3}}}\end{matrix}}{\begin{matrix}{1 - {0.1514\; {DPR}_{1}} +} \\{{0.03173\; {DPR}_{1}^{2}} + {0.0003673\; {DPR}_{1}^{3}}}\end{matrix}}\left\lbrack \frac{\begin{matrix}{\left( {{Ra}\text{-}1} \right)\left( {{Ra}\text{-}2} \right)\left( {{Ra}\text{-}4} \right)} \\{\left( {{Ra}\text{-}6} \right)\left( {{Ra}\text{-}8} \right)\left( {{Ra}\text{-}12} \right)}\end{matrix}}{\begin{matrix}{\left( {10\text{-}1} \right)\left( {10\text{-}2} \right)\left( {10\text{-}4} \right)} \\{\left( {10\text{-}6} \right)\left( {10\text{-}8} \right)\left( {10\text{-}12} \right)}\end{matrix}} \right\rbrack}$ ${E\; 12} = {\frac{\begin{matrix}{51.67 + {18.94\; {DPR}_{1}} +} \\{{21.57\; {DPR}_{1}^{2}} + {21.57\; {DPR}_{1}^{3}}}\end{matrix}}{\begin{matrix}{1 + {1.183\; {DPR}_{1}} +} \\{{0.5513\; {DPR}_{1}^{2}} - {0.00004359\; {DPR}_{1}^{3}}}\end{matrix}}\left\lbrack \frac{\begin{matrix}{\left( {{Ra}\text{-}1} \right)\left( {{Ra}\text{-}2} \right)\left( {{Ra}\text{-}4} \right)} \\{\left( {{Ra}\text{-}6} \right)\left( {{Ra}\text{-}8} \right)\left( {{Ra}\text{-}10} \right)}\end{matrix}}{\begin{matrix}{\left( {12\text{-}1} \right)\left( {12\text{-}2} \right)\left( {12\text{-}4} \right)} \\{\left( {12\text{-}6} \right)\left( {12\text{-}8} \right)\left( {12\text{-}10} \right)}\end{matrix}} \right\rbrack}$

1. Microchannel apparatus, comprising: a first channel extending in afirst direction; a second channel extending in a second direction; and athird channel extending in the second direction; a fourth channelextending in the second direction; and a fifth channel extending in thesecond direction; wherein the first and second directions aresubstantially coplanar; wherein the second and third channels areadjacent and parallel; wherein the first channel is not parallel toeither the second or third channels; wherein the first channel isconnected to the second channel and the third channels via a first gate;wherein the third channel is positioned farther in the first directionthan the second channel; wherein the third channel comprises amicrochannel; wherein the second channel comprises a microchannel;wherein the second channel has an opening with a first cross-sectionalarea and the third channel has an opening with a second cross-sectionalarea; wherein the first gate has a cross-sectional area that is smallerthan the sum of first and second cross-sectional areas and the wallcross-sectional area between them; wherein the fourth and fifth channelsare adjacent and parallel; wherein the first channel is connected to thefourth channel and the fifth channels via a second gate; wherein thefourth and fifth channels are positioned farther in the first directionthan the third channel; wherein the fourth channel comprises amicrochannel; wherein the fifth channel comprises a microchannel;wherein the fourth channel has an opening with a third cross-sectionalarea and the fifth channel has an opening with a fourth cross-sectionalarea; wherein the second gate has a cross-sectional area that is smallerthan the sum of third and fourth cross-sectional areas and the wallcross-sectional area between them; and wherein the cross-sectional areaof the first gate differs from that of the cross-sectional area of thesecond gate.
 2. The microchannel apparatus of claim 1 wherein the firstgate has a cross-sectional area between 2-98% of the combinedcross-sectional areas of the connecting microchannels served by thefirst gate.
 3. The microchannel apparatus of claim 1 wherein theapparatus is a laminate and the first gate comprises a sheet with across-bar. 4-9. (canceled)
 10. A method of distributing flow from amanifold through a connecting channel matrix, comprising: passing afluid through a manifold inlet and into a manifold having the followingcharacteristics: the height of the manifold (h_(m2m)) is 2 mm or less;the length of the manifold (L_(m2m)) is 7.5 cm or greater; the length ofan optional straightening channel portion (L₂) divided by L_(m2m) isless than 6; passing the fluid into the manifold with a momentum (Mo) ofat least 0.05 maintaining the DPR₂ ratio at 2 or greater or maintaininga DPR₃ ratio of 0.9 or less; and distributing the fluid from themanifold into at least 2 channels which are connected to the manifold,with a quality index factor as a function of connecting channel areas ofQ(Ra)=0.0008135Ra ⁶−0.03114Ra ⁵+0.4519Ra ⁴−3.12Ra ³+11.22Ra²−23.9Ra+39.09.
 11. The method of claim 10 wherein R_(a) is equal to orless than
 12. 12. The method of claim 10 wherein R_(a) is equal to orless than
 3. 13. The method of claim 11 wherein the fluid flow ratethrough the manifold is maintained such that the quantity{*0.058+0.0023(ln Re)²(D)*/L_(M2M)} is less than 0.01, where Re isReynolds number.
 14. The method of claim 11 wherein FA is less than0.01. 15-20. (canceled)
 21. A method of distributing flow from amanifold through a connecting channel matrix, comprising: passing afluid through a manifold inlet and into a manifold such that the fluidpasses through a first portion of a manifold in a first flow regime andpasses through a second portion of a manifold in a second flow regimewherein the manifold has the following characteristics: the height ofthe manifold (h_(m2m)) is 2 mm or less; the length of an optionalstraightening channel portion (L₂) divided by L_(m2m) is less than 6;maintaining the DPR₂ ratio at 2 or greater or maintaining a DPR₃ ratioof 0.9 or less; and distributing the fluid from the manifold into atleast 2 channels, which are connected to the manifold, with a qualityindex factor as a function of connecting channel areas ofQ(Ra)=0.0008135Ra ⁶−0.03114Ra ⁵+0.4519Ra ⁴−3.12Ra ³+11.22Ra²−23.9Ra+39.09.
 22. The method of claim 21 wherein the first flow regimeis turbulent and second flow regime is transitional.
 23. The method ofclaim 22 wherein R_(a) is equal to or less than
 12. 24. The method ofclaim 23 further comprising passing the fluid through a macromanifoldthat is connected to the manifold inlet. 25-31. (canceled)